2024
Torres, L. E. F. Foa; Roche, S.
A non-Hermitian loop for a quantum measurement Journal Article Forthcoming
In: Forthcoming.
BibTeX | Links:
@article{nokey,
title = {A non-Hermitian loop for a quantum measurement},
author = {L. E. F. {Foa Torres} and S. Roche},
url = {https://arxiv.org/abs/2408.04629},
year = {2024},
date = {2024-08-08},
keywords = {},
pubstate = {forthcoming},
tppubtype = {article}
}
Vicencio, R. A.; Román-Cortés, D.; Rubio-Saldías, M.; Vildoso, P.; Torres, L. E. F. Foa
Non-Reciprocal Coupling in Photonics Journal Article Forthcoming
In: Forthcoming.
BibTeX | Links:
@article{nokey,
title = {Non-Reciprocal Coupling in Photonics},
author = {R. A. Vicencio and D. Rom\'{a}n-Cort\'{e}s and M. Rubio-Sald\'{i}as and P. Vildoso and L. E. F. {Foa Torres}},
url = {https://arxiv.org/abs/2407.18174},
year = {2024},
date = {2024-07-25},
keywords = {},
pubstate = {forthcoming},
tppubtype = {article}
}
Efremov, D. V.; Ccuiro, W.; Torres, L. E. F. Foa; Kiselev, M. N.
Breaking of Lorentz invariance caused by the interplay between spin-orbit interaction and transverse phonon modes in quantum wires Journal Article Forthcoming
In: Forthcoming.
BibTeX | Links:
@article{nokey,
title = {Breaking of Lorentz invariance caused by the interplay between spin-orbit interaction and transverse phonon modes in quantum wires},
author = {D. V. Efremov and W. Ccuiro and L. E. F. {Foa Torres} and M. N. Kiselev},
url = {https://arxiv.org/abs/2407.08613},
year = {2024},
date = {2024-07-11},
urldate = {2024-07-11},
keywords = {},
pubstate = {forthcoming},
tppubtype = {article}
}
Romeral, J. Martínez; Torres, L. E. F. Foa; Roche, S
Wavefunction collapse driven by non-Hermitian disturbance Journal Article
In: Journal of Physics Communications, vol. 8, pp. 071001, 2024.
BibTeX | Links:
@article{nokey,
title = {Wavefunction collapse driven by non-Hermitian disturbance},
author = {J. Mart\'{i}nez Romeral and L. E. F. {Foa Torres} and S Roche},
doi = {10.1088/2399-6528/ad5b37},
year = {2024},
date = {2024-07-02},
urldate = {2024-07-02},
journal = {Journal of Physics Communications},
volume = {8},
pages = {071001},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Pérez, G. O’Ryan; Dueñas, J. Medina; Guzmán-Silva, D.; Torres, L. E. F. Foa; Hermann-Avigliano, C.
Transport of non-classical light mediated by topological domain walls in a SSH photonic lattice Journal Article
In: Scientific Reports, vol. 14, pp. 12435, 2024.
BibTeX | Links:
@article{nokey,
title = {Transport of non-classical light mediated by topological domain walls in a SSH photonic lattice},
author = {G. O’Ryan P\'{e}rez and J. Medina Due\~{n}as and D. Guzm\'{a}n-Silva and L. E. F. {Foa Torres} and C. Hermann-Avigliano},
doi = {10.1038/s41598-024-63321-3},
year = {2024},
date = {2024-05-30},
journal = {Scientific Reports},
volume = {14},
pages = {12435},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Jangjan, M.; Li, L.; Torres, L. E. F. Foa; Hosseini, M. V.
Topological phases of commensurate or incommensurate non-Hermitian Su-Schrieffer-Heeger lattices Journal Article
In: Physical Review B, vol. 109, pp. 205142, 2024.
BibTeX | Links:
@article{nokey,
title = {Topological phases of commensurate or incommensurate non-Hermitian Su-Schrieffer-Heeger lattices},
author = {M. Jangjan and L. Li and L. E. F. {Foa Torres} and M. V. Hosseini},
doi = {10.1103/PhysRevB.109.205142},
year = {2024},
date = {2024-05-21},
urldate = {2024-05-21},
journal = {Physical Review B},
volume = {109},
pages = {205142},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Mella, J. D.; Torres, L. E. F. Foa; Troncoso, R. E.
Chiral magnon-polaron edge states in Heisenberg-Kitaev magnets Journal Article Forthcoming
In: Forthcoming.
BibTeX | Links:
@article{nokey,
title = {Chiral magnon-polaron edge states in Heisenberg-Kitaev magnets},
author = {J. D. Mella and L. E. F. {Foa Torres} and R. E. Troncoso},
url = {https://arxiv.org/abs/2405.18644},
year = {2024},
date = {2024-05-08},
keywords = {},
pubstate = {forthcoming},
tppubtype = {article}
}
Barriga, E.; Torres, L. E. F. Foa; Cardenas, C.
Floquet Engineering of a Diatomic Molecule Through a Bichromatic Radiation Field Journal Article
In: Journal of Chemical Theory and Computation , vol. 20, pp. 2559, 2024.
BibTeX | Links:
@article{nokey,
title = {Floquet Engineering of a Diatomic Molecule Through a Bichromatic Radiation Field},
author = {E. Barriga and L. E. F. {Foa Torres} and C. Cardenas},
url = {https://arxiv.org/abs/2311.13697},
doi = {10.1021/acs.jctc.3c01277},
year = {2024},
date = {2024-03-13},
urldate = {2023-11-22},
journal = {Journal of Chemical Theory and Computation },
volume = {20},
pages = {2559},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
2023
Mella, J. D.; Calvo, H. L.; Torres, L. E. F. Foa
Entangled States Induced by Electron–Phonon Interaction in Two-Dimensional Materials Journal Article
In: Nano Letters, vol. 23, pp. 11013, 2023.
BibTeX | Links:
@article{nokey,
title = {Entangled States Induced by Electron\textendashPhonon Interaction in Two-Dimensional Materials},
author = {J. D. {Mella} and H. L. Calvo and L. E. F. {Foa Torres}},
url = {https://doi.org/10.1021/acs.nanolett.3c03316},
doi = {10.1021/acs.nanolett.3c03316},
year = {2023},
date = {2023-11-20},
journal = {Nano Letters},
volume = {23},
pages = {11013},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
2022
Jangjan, M.; Torres, L. E. F. Foa; Hosseini, M. V.
Floquet topological phase transitions in a periodically quenched dimer Journal Article
In: Physical Review B, vol. 102, pp. 224306, 2022.
BibTeX | Links:
@article{nokey,
title = {Floquet topological phase transitions in a periodically quenched dimer},
author = {M. Jangjan and L. E. F. {Foa Torres} and M. V. Hosseini},
url = {https://doi.org/10.1103/PhysRevB.106.224306},
doi = {10.1103/PhysRevB.106.224306},
year = {2022},
date = {2022-12-10},
urldate = {2022-12-10},
journal = {Physical Review B},
volume = {102},
pages = {224306},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Cáceres-Aravena, G.; Real, B.; D. Guzmán-Silva,; Amo, A.; Torres, L. E. F. Foa; Vicencio, R. A.
Experimental observation of edge states in SSH-Stub photonic lattices Journal Article
In: Physical Review Research, vol. 4, no. 013185, 2022.
@article{caceres-aravena2022,
title = {Experimental observation of edge states in SSH-Stub photonic lattices},
author = {G. C\'{a}ceres-Aravena and B. Real and D. Guzm\'{a}n-Silva, and A. Amo and L. E. F. {Foa Torres} and R. A. Vicencio},
url = {https://journals.aps.org/prresearch/abstract/10.1103/PhysRevResearch.4.013185},
doi = {10.1103/PhysRevResearch.4.013185},
year = {2022},
date = {2022-03-07},
journal = {Physical Review Research},
volume = {4},
number = {013185},
abstract = {We reveal unconventional edge states in a one-dimensional Stub lattice of coupled waveguides with staggered hoppings. The edge states appear for the same values of hoppings as topological edge states in the Su-Schrieffer-Heeger model. They have different energies depending on the lattice termination and present a remarkable robustness against certain types of disorder. We evidence experimentally the phase transition at which these edge states appear, opening the door to the engineering of one-dimensional lattices with localized edge modes whose energy and location can be controlled at will.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Dueñas, J. Medina; Calvo, H. L.; Torres, L. E. F. Foa
Copropagating edge states produced by the interaction between electrons and chiral phonons in two-dimensional materials Journal Article
In: Physical Review Letters, vol. 128, pp. 066801, 2022.
@article{medina-duenas2022,
title = {Copropagating edge states produced by the interaction between electrons and chiral phonons in two-dimensional materials},
author = {J. {Medina Due\~{n}as} and H. L. Calvo and L. E. F. {Foa Torres}},
url = {https://arxiv.org/abs/2109.03815},
doi = {https://doi.org/10.1103/PhysRevLett.128.066801},
year = {2022},
date = {2022-02-07},
journal = {Physical Review Letters},
volume = {128},
pages = {066801},
abstract = {Unlike the chirality of electrons, the intrinsic chirality of phonons has only surfaced in recent years. Here, we report on the effects of the interaction between electrons and chiral phonons in two-dimensional materials by using a nonperturbative solution. We show that chiral phonons introduce inelastic Umklapp processes resulting in copropagating edge states that coexist with a continuum. Transport simulations further reveal the robustness of the edge states. Our results hint on the possibility of having a metal embedded with hybrid electron-phonon states of matter.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Mella, J.; Torres, L. E. F. Foa
Robustness of spin-polarized edge states in a two-dimensional topological semimetal without inversion symmetry Journal Article
In: Physical Review B, vol. 105, pp. 075403, 2022.
@article{mella2021,
title = {Robustness of spin-polarized edge states in a two-dimensional topological semimetal without inversion symmetry},
author = {J. Mella and L. E. F. {Foa Torres}},
url = {https://arxiv.org/abs/2107.12956},
doi = {https://doi.org/10.1103/PhysRevB.105.075403},
year = {2022},
date = {2022-01-27},
journal = {Physical Review B},
volume = {105},
pages = {075403},
abstract = {Three-dimensional topological gapless phases have attracted significant attention due to their unique electronic properties. One of the flagships is the Weyl semimetals, which requires breaking time-reversal or inversion symmetry in three dimensions. In two dimensions, the dimensionality reduction requires imposing an additional symmetry, thereby weakening the phase. Like its three-dimensional counterpart, these two-dimensional Weyl semimetals present edge states directly related to Weyl nodes. The direct comparison with the edge states in zigzag-like terminated graphene ribbons is unavoidable, offering the question of how robust these states are and their differences. Here we benchmark the robustness of the edge states in two-dimensional Weyl semimetals with those present in zigzag graphene ribbons. To such end, we use a Dirac Hamiltonian model proposed by Young and Kane, adding new terms for inducing a two-dimensional Weyl semimetal phase and use a scattering picture for the transport calculation. Our results show that despite having a similar electronic band structure, the edge states of two-dimensional Weyl semimetal are more robust against vacancies than graphene ribbons. We attribute this enhanced robustness to a crucial role of the spin degree of freedom in the former case.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
2021
Torres, L. E. F. Foa; Valenzuela, S. O.
A valley of opportunities Journal Article
In: Physics World, vol. 11, pp. 43, 2021, ISSN: 2058-7058.
BibTeX | Links:
@article{foatorres_2021_valley,
title = {A valley of opportunities},
author = {L. E. F. {Foa Torres} and S. O. Valenzuela},
url = {https://t.co/ybNNHDPFUF},
doi = {https://doi.org/10.1088/2058-7058/34/11/40},
issn = {2058-7058},
year = {2021},
date = {2021-11-01},
journal = {Physics World},
volume = {11},
pages = {43},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Duenas, J. Medina; Pérez, G. O'Ryan; Hermann-Avigliano, Carla; Torres, L. E. F. Foa
Quadrature protection of squeezed states in a one-dimensional topological insulator Journal Article
In: Quantum, vol. 5, pp. 526, 2021.
@article{medina-duenas2021,
title = {Quadrature protection of squeezed states in a one-dimensional topological insulator},
author = {J. {Medina Duenas} and G. O'{Ryan P\'{e}rez} and Carla Hermann-Avigliano and L. E. F. {Foa Torres}},
url = {https://arxiv.org/abs/2106.00869},
doi = {10.22331/q-2021-08-17-526},
year = {2021},
date = {2021-08-17},
journal = {Quantum},
volume = {5},
pages = {526},
abstract = {What is the role of topology in the propagation of quantum light in photonic lattices? We address this question by studying the propagation of squeezed states in a topological one-dimensional waveguide array, benchmarking our results with those for a topologically trivial localized state, and studying their robustness against disorder. Specifically, we study photon statistics, one-mode and two-mode squeezing, and entanglement generation when the localized state is excited with squeezed light. These quantum properties inherit the shape of the localized state but, more interestingly, and unlike in the topologically trivial case, we find that propagation of squeezed light in a topologically protected state robustly preserves the phase of the squeezed quadrature as the system evolves. We show how this latter topological advantage can be harnessed for quantum information protocols.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Berdakin, M; Rodriguez-Mena, Esteban A; Torres, L. E. F. Foa
Spin-polarized tunable photocurrents Journal Article
In: Nano Letters, vol. 21, pp. 3177, 2021.
@article{berdakin2020,
title = {Spin-polarized tunable photocurrents},
author = {M Berdakin and Esteban A Rodriguez-Mena and L. E. F. {Foa Torres}},
url = {https://arxiv.org/abs/2010.11883},
doi = {https://doi.org/10.1021/acs.nanolett.1c00420},
year = {2021},
date = {2021-04-05},
journal = {Nano Letters},
volume = {21},
pages = {3177},
abstract = {Harnessing the unique features of topological materials for the development of a new generation of topological based devices is a challenge of paramount importance. Using Floquet scattering theory combined with atomistic models we study the interplay between laser illumination, spin and topology in a two-dimensional material with spin-orbit coupling. Starting from a topological phase, we show how laser illumination can selectively disrupt the topological edge states depending on their spin. This is manifested by the generation of pure spin currents and spin-polarized charge photocurrents under linearly and circularly polarized laser-illumination, respectively. Our results open a path for the generation and control of spin-polarized photocurrents.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Huamán, A.; Torres, L. E. F. Foa; Balseiro, C. A.; Usaj, Gonzalo
Quantum Hall edge states under periodic driving: A Floquet induced chirality switch Journal Article
In: Physical Review Research, vol. 3, pp. 013201, 2021.
@article{huaman2021,
title = {Quantum Hall edge states under periodic driving: A Floquet induced chirality switch},
author = {A. Huam\'{a}n and L. E. F. {Foa Torres} and C. A. Balseiro and Gonzalo Usaj},
url = {https://journals.aps.org/prresearch/abstract/10.1103/PhysRevResearch.3.013201},
doi = {10.1103/PhysRevResearch.3.013201},
year = {2021},
date = {2021-03-04},
journal = {Physical Review Research},
volume = {3},
pages = {013201},
abstract = {We report on the fate of the quantum Hall effect in graphene under intense laser illumination. By using Floquet theory combined with both a low energy description and full tight-binding models, we clarify the selection rules, the quasienergy band structure, as well as their connection with the two-terminal and multiterminal conductance in a device setup as relevant for experiments. We show that the well-known dynamical gaps that appear in the Floquet spectrum at ±ℏΩ/2 lead to a switch-off of the quantum Hall edge transport for different edge terminations except for the armchair one, where two terms cancel out exactly. More interestingly, we show that near the Dirac point changing the laser polarization (circular right or circular left) controls the Hall conductance, by allowing to switch it on or off, or even by flipping its sign, thereby reversing the chirality of the edge states. This might lead to new avenues to fully control topologically protected transport.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Giustino, Feliciano; Bibes, Manuel; Lee, Jin Hong; Trier, Felix; Valentí, Roser; Winter, Stephen M; Son, Young-Woo; Taillefer, Louis; Heil, Christoph; Figueroa, Adriana I; Plaçais, Bernard; Wu, QuanSheng; Yazyev, Oleg V; Bakkers, Erik P A M; Nygård, Jesper; Forn-Diaz, Pol; de Franceschi, Silvano; Torres, Luis E F Foa; McIver, James; Kumar, Anshuman; Low, Tony; Galceran, Regina; Valenzuela, Sergio; Costache, Marius Vasile; Manchon, Aurélien; Kim, Eun-Ah; Schleder, Gabriel Ravanhani; Fazzio, Adalberto; Roche, Stephan
The 2021 Quantum Materials Roadmap Journal Article
In: Journal of Physics: Materials, vol. 3, pp. 042006, 2021.
@article{10.1088/2515-7639/abb74e,
title = {The 2021 Quantum Materials Roadmap},
author = {Feliciano Giustino and Manuel Bibes and Jin Hong Lee and Felix Trier and Roser Valent\'{i} and Stephen M Winter and Young-Woo Son and Louis Taillefer and Christoph Heil and Adriana I Figueroa and Bernard Pla\c{c}ais and QuanSheng Wu and Oleg V Yazyev and Erik P A M Bakkers and Jesper Nygr{a}rd and Pol Forn-Diaz and Silvano de Franceschi and Luis E F {Foa Torres} and James McIver and Anshuman Kumar and Tony Low and Regina Galceran and Sergio Valenzuela and Marius Vasile Costache and Aur\'{e}lien Manchon and Eun-Ah Kim and Gabriel Ravanhani Schleder and Adalberto Fazzio and Stephan Roche},
url = {https://iopscience.iop.org/article/10.1088/2515-7639/abb74e},
year = {2021},
date = {2021-01-19},
journal = {Journal of Physics: Materials},
volume = {3},
pages = {042006},
abstract = {In recent years, the notion of “Quantum Materials” has emerged as a powerful unifying concept across diverse fields of science and engineering, from condensed-matter and cold-atom physics to materials science and quantum computing. Beyond traditional quantum materials such as unconventional superconductors, heavy fermions, and multiferroics, the field has significantly expanded to encompass topological quantum matter, two-dimensional materials and their van der Waals heterostructures, Moir\'{e} materials, Floquet time crystals, as well as materials and devices for quantum computation with Majorana fermions. In this Roadmap collection we aim to capture a snapshot of the most recent developments in the field, and to identify outstanding challenges and emerging opportunities. The format of the Roadmap, whereby experts in each discipline share their viewpoint and articulate their vision for quantum materials, reflects the dynamic and multifaceted nature of this research area, and is meant to encourage exchanges and discussions across traditional disciplinary boundaries. It is our hope that this collective vision will contribute to sparking new fascinating questions and activities at the intersection of materials science, condensed matter physics, device engineering, and quantum information, and to shaping a clearer landscape of quantum materials science as a new frontier of interdisciplinary scientific inquiry.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
2020
Torres, L E F Foa
Digging into the 3D Quantum Hall Effect [Viewpoint] Journal Article
In: Physics, vol. 13, pp. 170, 2020.
@article{foa_torres_3dQHE,
title = {Digging into the 3D Quantum Hall Effect [Viewpoint]},
author = {L E F {Foa Torres}},
url = {https://physics.aps.org/articles/pdf/10.1103/Physics.13.170},
doi = {10.1103/Physics.13.170 },
year = {2020},
date = {2020-11-09},
journal = {Physics},
volume = {13},
pages = {170},
abstract = {Theorists invoke electron-phonon interactions to explain the recent observation of the quantum Hall effect in a 3D electronic system.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Aguilera, Esteban; Jaeschke-Ubiergo, R; Vidal-Silva, N; Torres, Luis E F Foa; Nunez, A S
Topological magnonics in the two-dimensional van der Waals magnet CrI3 Journal Article
In: Physical Review B, vol. 102, no. 2, pp. 024409, 2020, ISSN: 2469-9950.
@article{ISI:000545539000011,
title = {Topological magnonics in the two-dimensional van der Waals magnet CrI3},
author = {Esteban Aguilera and R Jaeschke-Ubiergo and N Vidal-Silva and Luis E F {Foa Torres} and A S Nunez},
url = {https://arxiv.org/abs/2002.05266},
doi = {10.1103/PhysRevB.102.024409},
issn = {2469-9950},
year = {2020},
date = {2020-07-01},
journal = {Physical Review B},
volume = {102},
number = {2},
pages = {024409},
abstract = {We report on the magnon spectrum of Kitaev-Heisenberg magnets and
extract the parameters to model a two-dimensional CrI3. Our minimal spin
Hamiltonian includes a contribution stemming from a Heisenberg,
isotropic exchange, and a contribution arising from a Kitaev
interaction, anisotropic and frustrated exchange. Our calculations
reveal a gap that opens at the K and K' points and the topological
nature of the magnons which lead to the thermal Hall effect.
Furthermore, we calculate the magnon spectrum of nanoribbons
illustrating the corresponding edge states.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
extract the parameters to model a two-dimensional CrI3. Our minimal spin
Hamiltonian includes a contribution stemming from a Heisenberg,
isotropic exchange, and a contribution arising from a Kitaev
interaction, anisotropic and frustrated exchange. Our calculations
reveal a gap that opens at the K and K' points and the topological
nature of the magnons which lead to the thermal Hall effect.
Furthermore, we calculate the magnon spectrum of nanoribbons
illustrating the corresponding edge states.
Calvo, Hernan L; Vargas, Jose E Barrios; Torres, Luis E F Foa
Floquet boundary states in AB-stacked graphite Journal Article
In: Physical Review B, vol. 101, no. 7, pp. 075424, 2020, ISSN: 2469-9950.
@article{ISI:000514315800004,
title = {Floquet boundary states in AB-stacked graphite},
author = {Hernan L Calvo and Jose E Barrios Vargas and Luis E F {Foa Torres}},
url = {https://arxiv.org/abs/1911.02144},
doi = {10.1103/PhysRevB.101.075424},
issn = {2469-9950},
year = {2020},
date = {2020-02-01},
journal = {Physical Review B},
volume = {101},
number = {7},
pages = {075424},
abstract = {We report on the effect of laser illumination with circularly polarized
light on the electronic structure of AB-stacked graphite samples. By
using Floquet theory in combination with Green's function techniques, we
find that the polarized light induces band-gap openings at the Floquet
zone edge h Omega/2, bridged by chiral boundary states. These states
propagate mainly along the borders of the constituting layers as
evidenced by the time-averaged local density of states and the
probability current density in several geometries. Semianalytic
calculations of the Chern number suggest that these states are of
topological nature, similar to those found in illuminated 2D samples
like monolayer and bilayer graphene. These states are promising
candidates for the realization of a three-dimensional version of the
quantum Hall effect for Floquet systems.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
light on the electronic structure of AB-stacked graphite samples. By
using Floquet theory in combination with Green's function techniques, we
find that the polarized light induces band-gap openings at the Floquet
zone edge h Omega/2, bridged by chiral boundary states. These states
propagate mainly along the borders of the constituting layers as
evidenced by the time-averaged local density of states and the
probability current density in several geometries. Semianalytic
calculations of the Chern number suggest that these states are of
topological nature, similar to those found in illuminated 2D samples
like monolayer and bilayer graphene. These states are promising
candidates for the realization of a three-dimensional version of the
quantum Hall effect for Floquet systems.
Cáceres-Aravena, G.; Torres, L. E. F. Foa; Vicencio, R. A.
Topological and flat-band states induced by hybridized linear interactions in one-dimensional photonic lattices Journal Article
In: Physical Review A, vol. 102, no. 2, pp. 023505, 2020.
@article{caceres-aravena_topological_2020,
title = {Topological and flat-band states induced by hybridized linear interactions in one-dimensional photonic lattices},
author = { G. C\'{a}ceres-Aravena and L. E. F. {Foa Torres} and R. A. Vicencio},
url = {https://arxiv.org/abs/2004.11932},
doi = {10.1103/PhysRevA.102.023505},
year = {2020},
date = {2020-01-01},
urldate = {2020-08-08},
journal = {Physical Review A},
volume = {102},
number = {2},
pages = {023505},
abstract = {We report on a study of a one-dimensional linear photonic lattice hosting, simultaneously, fundamental and dipolar modes at every site. We show how, thanks to the coupling between different orbital modes, this minimal model exhibits rich transport and topological properties. By varying the detuning coefficient we find a regime where bands become flatter (with reduced transport) and a second regime, where both bands connect at a gap-closing transition (with enhanced transport). We detect an asymmetric transport due to the asymmetric intermode coupling and a linear energy exchange mechanism between modes. Further analysis shows that the bands have a topological transition with a nontrivial Zak phase which leads to the appearance of edge states in a finite system. Finally, for zero detuning, we found a symmetric condition for coupling constants, where the linear spectrum becomes completely flat, with states fully localized in space occupying only two lattice sites.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Torres, L E F Foa; Roche, S; Charlier, J -C
Introduction to Graphene-Based Nanomaterials: From Electronic Structure to Quantum Transport (second edition) Book
Cambridge University Press, 2020, ISBN: 9781108476997.
BibTeX | Links:
@book{foa_torres_introduction_2020,
title = {Introduction to Graphene-Based Nanomaterials: From Electronic Structure to Quantum Transport (second edition)},
author = {L E F {Foa Torres} and S Roche and J -C Charlier},
url = {https://www.cambridge.org/us/academic/subjects/physics/condensed-matter-physics-nanoscience-and-mesoscopic-physics/introduction-graphene-based-nanomaterials-electronic-structure-quantum-transport-2nd-edition?format=HB\&isbn=9781108476997},
isbn = {9781108476997},
year = {2020},
date = {2020-01-01},
urldate = {2020-06-25},
publisher = {Cambridge University Press},
keywords = {},
pubstate = {published},
tppubtype = {book}
}
2019
Rodriguez-Mena, Esteban A; Torres, L E F Foa
Topological signatures in quantum transport in anomalous Floquet-Anderson insulators Journal Article
In: Physical Review B, vol. 100, no. 19, pp. 195429, 2019, ISSN: 2469-9950.
@article{ISI:000498851300011,
title = {Topological signatures in quantum transport in anomalous Floquet-Anderson insulators},
author = {Esteban A Rodriguez-Mena and L E F {Foa Torres}},
url = {https://arxiv.org/abs/1909.05957},
doi = {10.1103/PhysRevB.100.195429},
issn = {2469-9950},
year = {2019},
date = {2019-11-01},
journal = {Physical Review B},
volume = {100},
number = {19},
pages = {195429},
abstract = {Topological states require the presence of extended bulk states, as
usually found in the picture of energy bands and topological states
bridging the bulk gaps. But in driven systems this can be circumvented,
and one can get topological states coexisting with fully localized bulk
states, as in the case of the anomalous Floquet-Anderson insulator.
Here, we show the fingerprints of this peculiar topological phase in the
transport properties and their dependence on the disorder strength,
geometrical configuration (two-terminal and multiterminal setups), and
details of the driving protocol.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
usually found in the picture of energy bands and topological states
bridging the bulk gaps. But in driven systems this can be circumvented,
and one can get topological states coexisting with fully localized bulk
states, as in the case of the anomalous Floquet-Anderson insulator.
Here, we show the fingerprints of this peculiar topological phase in the
transport properties and their dependence on the disorder strength,
geometrical configuration (two-terminal and multiterminal setups), and
details of the driving protocol.
Torres, Luis E F Foa
A sudden twist Journal Article
In: Nature Physics, vol. 15, no. 10, pp. 988-989, 2019, ISSN: 1745-2473.
BibTeX | Links:
@article{ISI:000488590700009,
title = {A sudden twist},
author = {Luis E F {Foa Torres}},
url = {https://rdcu.be/bJgEY},
doi = {10.1038/s41567-019-0595-4},
issn = {1745-2473},
year = {2019},
date = {2019-10-01},
journal = {Nature Physics},
volume = {15},
number = {10},
pages = {988-989},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Torres, Luis E F Foa
Perspective on topological states of non-Hermitian lattices Journal Article
In: Journal of Physics: Materials, vol. 3, no. 1, pp. 014002, 2019, ISSN: 2515-7639, (Invited article for Focus Issue on Topological Matter).
@article{torres_perspective_2019,
title = {Perspective on topological states of non-Hermitian lattices},
author = {Luis E F {Foa Torres}},
url = {https://doi.org/10.1088%2F2515-7639%2Fab4092},
doi = {10.1088/2515-7639/ab4092},
issn = {2515-7639},
year = {2019},
date = {2019-01-01},
urldate = {2020-08-08},
journal = {Journal of Physics: Materials},
volume = {3},
number = {1},
pages = {014002},
abstract = {The search of topological states in non-Hermitian systems has gained a strong momentum over the last two years climbing to the level of an emergent research front. In this perspective we give an overview with a focus on connecting this topic to others like Floquet systems. Furthermore, using a simple scattering picture we discuss an interpretation of concepts like the Hamiltonian’s defectiveness, i.e. the lack of a full basis of eigenstates, crucial in many discussions of topological phases of non-Hermitian Hamiltonians.},
note = {Invited article for Focus Issue on Topological Matter},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Bajpai, U; Popescu, B S; Plecháč, P; Nikolić, B K; Torres, L E F Foa; Ishizuka, H; Nagaosa, N
Spatio-temporal dynamics of shift current quantum pumping by femtosecond light pulse Journal Article
In: Journal of Physics: Materials, vol. 2, no. 2, pp. 025004, 2019, ISSN: 2515-7639.
@article{bajpai_spatio-temporal_2019,
title = {Spatio-temporal dynamics of shift current quantum pumping by femtosecond light pulse},
author = {U Bajpai and B S Popescu and P Plech\'{a}\v{c} and B K Nikoli\'{c} and L E F {Foa Torres} and H Ishizuka and N Nagaosa},
url = {https://arxiv.org/abs/1803.04404},
doi = {10.1088/2515-7639/ab0a3e},
issn = {2515-7639},
year = {2019},
date = {2019-01-01},
urldate = {2020-08-08},
journal = {Journal of Physics: Materials},
volume = {2},
number = {2},
pages = {025004},
abstract = {Shift current\textemdasha photocurrent induced by light irradiating noncentrosymmetric materials in the absence of any bias voltage or built-in electric field\textemdashis one of the mechanisms of the so-called bulk photovoltaic effect. It has been traditionally described as a nonlinear optical response of a periodic solid to continuous wave light using a perturbative formula, which is linear in the intensity of light and which involves Berry connection describing the shift in the center of mass position of the Wannier wave function associated with the transition between the valence and conduction bands of the solid. Since shift current is solely due to off-diagonal elements of the nonequilibrium density matrix that encode quantum correlations, its peculiar space\textendashtime dynamics in response to femtosecond light pulse employed locally can be expected. To study such response requires to analyze realistic two-terminal devices, instead of traditional periodic solids, for which we choose paradigmatic Rice\textendashMele model sandwiched between two metallic electrodes and apply to it time-dependent nonequilibrium Green function algorithms scaling linearly in the number of time steps and capable of treating nonperturbative effects in the amplitude of external time-dependent fields. This reveals novel features: superballistic transport, signified by time dependence of the displacement of the photoexcited charge carriers from the spot where the femtosecond light pulse is applied toward the electrodes; and photocurrent quadratic in light intensity at subgap frequencies of light due to two-photon absorption processes that were missed in previous perturbative analyses. Furthermore, frequency dependence of the DC component of the photocurrent reveals shift current as a realization of nonadiabatic quantum charge pumping enabled by breaking of left\textendashright symmetry of the device structure. This demonstrates that a much wider class of systems, than the usually considered polar noncentrosymmetric bulk materials, can be exploited to generate nonzero DC component of photocurrent in response to unpolarized light and optimize shift-current-based solar cells and optoelectronic devices.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
2018
Berdakin, M; Vargas, J E Barrios; Torres, L E F Foa
Directional control of charge and valley currents in a graphene-based device Journal Article
In: Physical Chemistry Chemical Physics, vol. 20, no. 45, pp. 28720-28725, 2018, ISSN: 1463-9076.
@article{ISI:000451089900033,
title = {Directional control of charge and valley currents in a graphene-based device},
author = {M Berdakin and J E Barrios Vargas and L E F {Foa Torres}},
url = {https://chemrxiv.org/engage/chemrxiv/article-details/60c73f3f337d6cce34e264e7},
doi = {10.1039/c8cp04878a},
issn = {1463-9076},
year = {2018},
date = {2018-12-01},
journal = {Physical Chemistry Chemical Physics},
volume = {20},
number = {45},
pages = {28720-28725},
abstract = {We propose a directional switching effect in a metallic device. To this
end we exploit a graphene-based device with a three-terminal geometry in
the presence of a magnetic field. We show that unidirectional charge and
valley currents can be controlled by the Fermi energy and the magnetic
field direction in the active device. Interestingly, unidirectional
transport of charges and valleys is generated between two-terminals at
the same bias voltage. Furthermore, we quantify the valley
depolarization as a function of disorder concentration. Our results open
a way for active graphene-based valleytronics devices.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
end we exploit a graphene-based device with a three-terminal geometry in
the presence of a magnetic field. We show that unidirectional charge and
valley currents can be controlled by the Fermi energy and the magnetic
field direction in the active device. Interestingly, unidirectional
transport of charges and valleys is generated between two-terminals at
the same bias voltage. Furthermore, we quantify the valley
depolarization as a function of disorder concentration. Our results open
a way for active graphene-based valleytronics devices.
Alvarez, V M Martinez; Vargas, J E Barrios; Berdakin, M; Torres, L E F Foa
Topological states of non-Hermitian systems Journal Article
In: European Physical Journal-Special Topics, vol. 227, no. 12, pp. 1295-1308, 2018, ISSN: 1951-6355, (Invited short review for the special issue “Topological States of Matter: Theory and Applications”).
@article{ISI:000455553900002,
title = {Topological states of non-Hermitian systems},
author = {V M {Martinez Alvarez} and J E {Barrios Vargas} and M Berdakin and L E F {Foa Torres}},
url = {https://repositorio.uchile.cl/bitstream/handle/2250/169477/Topological_states.pdf?sequence=1\&isAllowed=y},
doi = {10.1140/epjst/e2018-800091-5},
issn = {1951-6355},
year = {2018},
date = {2018-12-01},
journal = {European Physical Journal-Special Topics},
volume = {227},
number = {12},
pages = {1295-1308},
abstract = {Recently, the search for topological states of matter has turned to
non-Hermitian systems, which exhibit a rich variety of unique properties
without Hermitian counterparts. Lattices modeled through non-Hermitian
Hamiltonians appear in the context of photonic systems, where one needs
to account for gain and loss, circuits of resonators, and also when
modeling the lifetime due to interactions in condensed matter systems.
Here we provide a brief overview of this rapidly growing subject, the
search for topological states and a bulk-boundary correspondence in
non-Hermitian systems.},
note = {Invited short review for the special issue “Topological States of Matter: Theory and Applications”},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
non-Hermitian systems, which exhibit a rich variety of unique properties
without Hermitian counterparts. Lattices modeled through non-Hermitian
Hamiltonians appear in the context of photonic systems, where one needs
to account for gain and loss, circuits of resonators, and also when
modeling the lifetime due to interactions in condensed matter systems.
Here we provide a brief overview of this rapidly growing subject, the
search for topological states and a bulk-boundary correspondence in
non-Hermitian systems.
Calvo, Hernan L; Luna, Javier S; Lago, Virginia Dal; Torres, Luis E F Foa
Robust edge states induced by electron-phonon interaction in graphene nanoribbons Journal Article
In: Physical Review B, vol. 98, no. 3, pp. 035423, 2018, ISSN: 2469-9950.
@article{ISI:000438855600002,
title = {Robust edge states induced by electron-phonon interaction in graphene nanoribbons},
author = {Hernan L Calvo and Javier S Luna and Virginia {Dal Lago} and Luis E F {Foa Torres}},
url = {https://arxiv.org/abs/1805.00576},
doi = {10.1103/PhysRevB.98.035423},
issn = {2469-9950},
year = {2018},
date = {2018-07-01},
journal = {Physical Review B},
volume = {98},
number = {3},
pages = {035423},
abstract = {The search of new means of generating and controlling topological states
of matter is at the front of many joint efforts, including band-gap
engineering by doping and light-induced topological states. Most of our
understading, however, is based on a single particle picture.
Topological states in systems including interaction effects, such as
electron-electron and electron-phonon, remain less explored. By
exploiting a nonperturbative and nonadiabatic picture, here we show how
the interaction between electrons and a coherent phonon mode can lead to
a band gap hosting edge states of topological origin. Further numerical
simulations witness the robustness of these states against different
types of disorder. Our results contribute to the search of topological
states, in this case in a minimal Fock space.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
of matter is at the front of many joint efforts, including band-gap
engineering by doping and light-induced topological states. Most of our
understading, however, is based on a single particle picture.
Topological states in systems including interaction effects, such as
electron-electron and electron-phonon, remain less explored. By
exploiting a nonperturbative and nonadiabatic picture, here we show how
the interaction between electrons and a coherent phonon mode can lead to
a band gap hosting edge states of topological origin. Further numerical
simulations witness the robustness of these states against different
types of disorder. Our results contribute to the search of topological
states, in this case in a minimal Fock space.
Lopez, J Chesta; Torres, L E F Foa; Nunez, A S
Multiterminal conductance at the surface of a Weyl semimetal Journal Article
In: Physical Review B, vol. 97, no. 12, pp. 125419, 2018, ISSN: 2469-9950.
@article{ISI:000427638900007,
title = {Multiterminal conductance at the surface of a Weyl semimetal},
author = {J {Chesta Lopez} and L E F {Foa Torres} and A S Nunez},
url = {https://repositorio.uchile.cl/bitstream/handle/2250/155800/item_85043982183.pdf?sequence=1\&isAllowed=y},
doi = {10.1103/PhysRevB.97.125419},
issn = {2469-9950},
year = {2018},
date = {2018-03-01},
journal = {Physical Review B},
volume = {97},
number = {12},
pages = {125419},
abstract = {Weyl semimetals are a new paradigmatic topological phase of matter
featuring a gapless spectrum. One of its most distinctive features is
the presence of Fermi arc surface states. Here, we report on atomistic
simulations of the dc conductance and quantum Hall response of a
minimalWeyl semimetal. By using scattering theory we show that a
quantized Hall conductance with a nonvanishing longitudinal conductance
emerges associated to the Fermi arc surface states with a remarkable
robustness to high concentrations of defects in the system.
Additionally, we predict that a slab of a Weyl semimetal with broken
time-reversal symmetry bears persistent currents fully determined by the
system size and the lattice parameters.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
featuring a gapless spectrum. One of its most distinctive features is
the presence of Fermi arc surface states. Here, we report on atomistic
simulations of the dc conductance and quantum Hall response of a
minimalWeyl semimetal. By using scattering theory we show that a
quantized Hall conductance with a nonvanishing longitudinal conductance
emerges associated to the Fermi arc surface states with a remarkable
robustness to high concentrations of defects in the system.
Additionally, we predict that a slab of a Weyl semimetal with broken
time-reversal symmetry bears persistent currents fully determined by the
system size and the lattice parameters.
Alvarez, V M Martinez; Vargas, J E Barrios; Torres, L E F Foa
Non-Hermitian robust edge states in one dimension: Anomalous localization and eigenspace condensation at exceptional points Journal Article
In: Physical Review B, vol. 97, no. 12, pp. 121401, 2018, ISSN: 2469-9950.
@article{ISI:000426779100002,
title = {Non-Hermitian robust edge states in one dimension: Anomalous localization and eigenspace condensation at exceptional points},
author = {V M {Martinez Alvarez} and J E {Barrios Vargas} and L E F {Foa Torres}},
url = {https://repositorio.uchile.cl/bitstream/handle/2250/169335/Non_hermitian.pdf?sequence=1\&isAllowed=y},
doi = {10.1103/PhysRevB.97.121401},
issn = {2469-9950},
year = {2018},
date = {2018-03-01},
journal = {Physical Review B},
volume = {97},
number = {12},
pages = {121401},
abstract = {Capital to topological insulators, the bulk-boundary correspondence ties
a topological invariant computed from the bulk (extended) states with
those at the boundary, which are hence robust to disorder. Here we put
forward a different ordering unique to non-Hermitian lattices whereby a
pristine system becomes devoid of extended states, a property which
turns out to be robust to disorder. This is enabled by a peculiar type
of non-Hermitian degeneracy where a macroscopic fraction of the states
coalesce at a single point with a geometrical multiplicity of 1.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
a topological invariant computed from the bulk (extended) states with
those at the boundary, which are hence robust to disorder. Here we put
forward a different ordering unique to non-Hermitian lattices whereby a
pristine system becomes devoid of extended states, a property which
turns out to be robust to disorder. This is enabled by a peculiar type
of non-Hermitian degeneracy where a macroscopic fraction of the states
coalesce at a single point with a geometrical multiplicity of 1.
2017
Lago, V Dal; Morell, E Suarez; Torres, L E F Foa
One-way transport in laser-illuminated bilayer graphene: A Floquet isolator Journal Article
In: Physical Review B, vol. 96, no. 23, pp. 235409, 2017, ISSN: 2469-9950.
@article{ISI:000417487200003,
title = {One-way transport in laser-illuminated bilayer graphene: A Floquet isolator},
author = {V {Dal Lago} and E Suarez Morell and L E F {Foa Torres}},
url = {https://repositorio.uchile.cl/bitstream/handle/2250/168735/One-way-transport.pdf?sequence=1\&isAllowed=y},
doi = {10.1103/PhysRevB.96.235409},
issn = {2469-9950},
year = {2017},
date = {2017-12-01},
journal = {Physical Review B},
volume = {96},
number = {23},
pages = {235409},
abstract = {We explore the Floquet band structure and electronic transport in
laser-illuminated bilayer graphene ribbons. By using a bias voltage
perpendicular to the graphene bilayer we show how to get one-way charge
and valley transport among two unbiased leads. In contrast to quantum
pumping, our proposal uses a different mechanism based on generating a
nonreciprocal band structure with a built-in directionality. The Floquet
states at one edge of a graphene layer become hybridized with the
continuum on the other layer, so the resulting band structure allows for
one-way transport as in an isolator. Our proof of concept may serve as a
building block for devices exploiting one-way states.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
laser-illuminated bilayer graphene ribbons. By using a bias voltage
perpendicular to the graphene bilayer we show how to get one-way charge
and valley transport among two unbiased leads. In contrast to quantum
pumping, our proposal uses a different mechanism based on generating a
nonreciprocal band structure with a built-in directionality. The Floquet
states at one edge of a graphene layer become hybridized with the
continuum on the other layer, so the resulting band structure allows for
one-way transport as in an isolator. Our proof of concept may serve as a
building block for devices exploiting one-way states.
Kalugin, Nikolai G; Jing, Lei; Morell, Eric Suarez; Dyer, Gregory C; Wickey, Lee; Ovezmyradov, Mekan; Grine, Albert D; Wanke, Michael C; Shaner, Eric A; Lau, Chun Ning; Torres, Luis E F Foa; Fistul, Mikhail V; Efetov, Konstantin B
Photoelectric polarization-sensitive broadband photoresponse from interface junction states in graphene Journal Article
In: 2D Materials, vol. 4, no. 1, 2017, ISSN: 2053-1583.
@article{ISI:000387051100002,
title = {Photoelectric polarization-sensitive broadband photoresponse from
interface junction states in graphene},
author = {Nikolai G Kalugin and Lei Jing and Eric Suarez Morell and Gregory C Dyer and Lee Wickey and Mekan Ovezmyradov and Albert D Grine and Michael C Wanke and Eric A Shaner and Chun Ning Lau and Luis E F Foa Torres and Mikhail V Fistul and Konstantin B Efetov},
doi = {10.1088/2053-1583/4/1/015002},
issn = {2053-1583},
year = {2017},
date = {2017-03-01},
journal = {2D Materials},
volume = {4},
number = {1},
abstract = {Graphene has established itself as a promising optoelectronic material.
Many details of the photoresponse (PR) mechanisms in graphene in the
THz-to-visible range have been revealed, however, new intricacies
continue to emerge. Interface junctions, formed at the boundaries
between parts of graphene with different number of layers or different
stacking orders, and making connection between electrical contacts,
provide another peculiar setup to establish PR. Here, we experimentally
demonstrate an enhanced polarization sensitive photoelectric PR in
graphene sheets containing interface junctions as compared to homogenous
graphene sheets in the visible, infrared, and THz spectral regions. Our
numerical simulations show that highly localized electronic states are
created at the interface junctions, and these states exhibit a unique
energy spectrum and enhanced probabilities for optical transitions. The
interaction of electrons from interface junction states with
electromagnetic fields generates a polarization-sensitive PR that is
maximal for the polarization direction perpendicular to the junction
interface.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Many details of the photoresponse (PR) mechanisms in graphene in the
THz-to-visible range have been revealed, however, new intricacies
continue to emerge. Interface junctions, formed at the boundaries
between parts of graphene with different number of layers or different
stacking orders, and making connection between electrical contacts,
provide another peculiar setup to establish PR. Here, we experimentally
demonstrate an enhanced polarization sensitive photoelectric PR in
graphene sheets containing interface junctions as compared to homogenous
graphene sheets in the visible, infrared, and THz spectral regions. Our
numerical simulations show that highly localized electronic states are
created at the interface junctions, and these states exhibit a unique
energy spectrum and enhanced probabilities for optical transitions. The
interaction of electrons from interface junction states with
electromagnetic fields generates a polarization-sensitive PR that is
maximal for the polarization direction perpendicular to the junction
interface.
2016
Ingaramo, L H; Torres, L E F Foa
Valley filtering by a line-defect in graphene: quantum interference and inversion of the filter effect Journal Article
In: Journal of Physics-Condensed Matter, vol. 28, no. 48, pp. 485302, 2016, ISSN: 0953-8984.
@article{ISI:000385676900001,
title = {Valley filtering by a line-defect in graphene: quantum interference and inversion of the filter effect},
author = {L H Ingaramo and L E F {Foa Torres}},
url = {https://arxiv.org/abs/1609.05769},
doi = {10.1088/0953-8984/28/48/485302},
issn = {0953-8984},
year = {2016},
date = {2016-12-01},
journal = {Journal of Physics-Condensed Matter},
volume = {28},
number = {48},
pages = {485302},
abstract = {Valley filters are crucial to any device exploiting the valley degree of
freedom. By using an atomistic model, we analyze the mechanism leading
to the valley filtering produced by a line-defect in graphene and show
how it can be inverted by external means. Thanks to a mode decomposition
applied to a tight-binding model we can resolve the different transport
channels in k-space while keeping a simple but accurate description of
the band structure, both close and further away from the Dirac point.
This allows the understanding of a destructive interference effect,
specifically a Fano resonance or antiresonance located on the p-side of
the Dirac point leading to a reduced conductance. We show that in the
neighborhood of this feature the valley filtering can be reversed by
changing the occupations with a gate voltage, the mechanism is explained
in terms of a valley-dependent Fano resonance splitting. Our results
open the door for enhanced control of valley transport in graphene-based
devices.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
freedom. By using an atomistic model, we analyze the mechanism leading
to the valley filtering produced by a line-defect in graphene and show
how it can be inverted by external means. Thanks to a mode decomposition
applied to a tight-binding model we can resolve the different transport
channels in k-space while keeping a simple but accurate description of
the band structure, both close and further away from the Dirac point.
This allows the understanding of a destructive interference effect,
specifically a Fano resonance or antiresonance located on the p-side of
the Dirac point leading to a reduced conductance. We show that in the
neighborhood of this feature the valley filtering can be reversed by
changing the occupations with a gate voltage, the mechanism is explained
in terms of a valley-dependent Fano resonance splitting. Our results
open the door for enhanced control of valley transport in graphene-based
devices.
Lovey, D A; Usaj, Gonzalo; Torres, L E F Foa; Balseiro, C A
Floquet bound states around defects and adatoms in graphene Journal Article
In: Physical Review B, vol. 93, no. 24, pp. 245434, 2016, ISSN: 2469-9950.
@article{ISI:000378816300004,
title = {Floquet bound states around defects and adatoms in graphene},
author = {D A Lovey and Gonzalo Usaj and L E F {Foa Torres} and C A Balseiro},
doi = {10.1103/PhysRevB.93.245434},
issn = {2469-9950},
year = {2016},
date = {2016-06-01},
journal = {Physical Review B},
volume = {93},
number = {24},
pages = {245434},
abstract = {Recent studies have focused on laser-induced gaps in graphene which have
been shown to have a topological origin, thereby hosting robust states
at the sample edges. While the focus has remainedmainly on these
topological chiral edge states, the Floquet bound states around defects
lack a detailed study. In this paper we present such a study covering
large defects of different shape and also vacancy-like defects and
adatoms at the dynamical gap at h Omega/2 (h Omega being the photon
energy). Our results, based on analytical calculations as well as
numerics for full tight-binding models, show that the bound states are
chiral and appear in a number which grows with the defect size.
Furthermore, while the bound states exist regardless of the type of the
defect's edge termination (zigzag, armchair, mixed), the spectrum is
strongly dependent on it. In the case of top adatoms, the bound state
quasienergies depend on the adatoms energy. The appearance of such bound
states might open the door to the presence of topological effects on the
bulk transport properties of dirty graphene.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
been shown to have a topological origin, thereby hosting robust states
at the sample edges. While the focus has remainedmainly on these
topological chiral edge states, the Floquet bound states around defects
lack a detailed study. In this paper we present such a study covering
large defects of different shape and also vacancy-like defects and
adatoms at the dynamical gap at h Omega/2 (h Omega being the photon
energy). Our results, based on analytical calculations as well as
numerics for full tight-binding models, show that the bound states are
chiral and appear in a number which grows with the defect size.
Furthermore, while the bound states exist regardless of the type of the
defect's edge termination (zigzag, armchair, mixed), the spectrum is
strongly dependent on it. In the case of top adatoms, the bound state
quasienergies depend on the adatoms energy. The appearance of such bound
states might open the door to the presence of topological effects on the
bulk transport properties of dirty graphene.
Torres, L E F Foa; Lago, V Dal; Morell, E Suarez
Crafting zero-bias one-way transport of charge and spin Journal Article
In: Physical Review B, vol. 93, no. 7, pp. 075438, 2016, ISSN: 2469-9950.
@article{ISI:000370841200006,
title = {Crafting zero-bias one-way transport of charge and spin},
author = {L E F {Foa Torres} and V {Dal Lago} and E Suarez Morell},
url = {https://repositorio.uchile.cl/bitstream/handle/2250/139102/Crafting-zero-bias-one-way-transport-of-charge-and-spin.pdf?sequence=1\&isAllowed=y},
doi = {10.1103/PhysRevB.93.075438},
issn = {2469-9950},
year = {2016},
date = {2016-02-01},
journal = {Physical Review B},
volume = {93},
number = {7},
pages = {075438},
abstract = {We explore the electronic structure and transport properties of a metal
on top of a (weakly coupled) two-dimensional topological insulator.
Unlike the widely studied junctions between topological nontrivial
Materials, the systems studied here allow for a unique band structure
and transport steering. First, states on the topological insulator layer
may coexist with the gapless bulk and, second, the edge states on one
edge can be selectively switched off, thereby leading to nearly perfect
directional transport of charge and spin even in the zero bias limit. We
illustrate these phenomena for Bernal stacked bilayer graphene with
Haldane or intrinsic spin-orbit terms and a perpendicular bias voltage.
This opens a path for realizing directed transport in Materials such as
van der Waals heterostructures, monolayer, and ultrathin topological
insulators.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
on top of a (weakly coupled) two-dimensional topological insulator.
Unlike the widely studied junctions between topological nontrivial
Materials, the systems studied here allow for a unique band structure
and transport steering. First, states on the topological insulator layer
may coexist with the gapless bulk and, second, the edge states on one
edge can be selectively switched off, thereby leading to nearly perfect
directional transport of charge and spin even in the zero bias limit. We
illustrate these phenomena for Bernal stacked bilayer graphene with
Haldane or intrinsic spin-orbit terms and a perpendicular bias voltage.
This opens a path for realizing directed transport in Materials such as
van der Waals heterostructures, monolayer, and ultrathin topological
insulators.
2015
Lago, V Dal; Atala, M; Torres, L E F Foa
Floquet topological transitions in a driven one-dimensional topological insulator Journal Article
In: Physical Review A, vol. 92, no. 2, pp. 023624, 2015, ISSN: 1050-2947.
@article{ISI:000359672200007,
title = {Floquet topological transitions in a driven one-dimensional topological insulator},
author = {V {Dal Lago} and M Atala and L E F {Foa Torres}},
doi = {10.1103/PhysRevA.92.023624},
issn = {1050-2947},
year = {2015},
date = {2015-08-01},
journal = {Physical Review A},
volume = {92},
number = {2},
pages = {023624},
abstract = {The Su-Schrieffer-Heeger model of polyacetylene is a paradigmatic
Hamiltonian exhibiting nontrivial edge states. By using Floquet theory
we study how the spectrum of this one-dimensional topological insulator
is affected by a time-dependent potential. In particular, we provide
evidence of the competition among different photon-assisted processes
and the native topology of the unperturbed Hamiltonian to settle the
resulting topology at different driving frequencies. While some regions
of the quasienergy spectrum develop new gaps hosting Floquet edge
states, the native gap can be dramatically reduced and the original edge
states may be destroyed or replaced by new Floquet edge states. Our
study is complemented by an analysis of the Zak phase applied to the
Floquet bands. Besides serving as a simple example for understanding the
physics of driven topological phases, our results could find a promising
testing ground in cold-matter experiments.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Hamiltonian exhibiting nontrivial edge states. By using Floquet theory
we study how the spectrum of this one-dimensional topological insulator
is affected by a time-dependent potential. In particular, we provide
evidence of the competition among different photon-assisted processes
and the native topology of the unperturbed Hamiltonian to settle the
resulting topology at different driving frequencies. While some regions
of the quasienergy spectrum develop new gaps hosting Floquet edge
states, the native gap can be dramatically reduced and the original edge
states may be destroyed or replaced by new Floquet edge states. Our
study is complemented by an analysis of the Zak phase applied to the
Floquet bands. Besides serving as a simple example for understanding the
physics of driven topological phases, our results could find a promising
testing ground in cold-matter experiments.
Calvo, H L; Torres, L E F Foa; Perez-Piskunow, P M; Balseiro, C A; Usaj, Gonzalo
Floquet interface states in illuminated three-dimensional topological insulators Journal Article
In: Physical Review B, vol. 91, no. 24, pp. 241404, 2015, ISSN: 2469-9950.
@article{ISI:000356129800001,
title = {Floquet interface states in illuminated three-dimensional topological insulators},
author = {H L Calvo and L E F {Foa Torres} and P M Perez-Piskunow and C A Balseiro and Gonzalo Usaj},
doi = {10.1103/PhysRevB.91.241404},
issn = {2469-9950},
year = {2015},
date = {2015-06-01},
journal = {Physical Review B},
volume = {91},
number = {24},
pages = {241404},
abstract = {Recent experiments showed that the surface of a three-dimensional
topological insulator develops gaps in the Floquet-Bloch band spectrum
when illuminated with a circularly polarized laser. These Floquet-Bloch
bands are characterized by nontrivial Chern numbers which only depend on
the helicity of the polarization of the radiation field. Here we propose
a setup consisting of a pair of counterrotating lasers, and show that
one-dimensional chiral states emerge at the interface between the two
lasers. These interface states turn out to be spin polarized and may
trigger interesting applications in the field of optoelectronics and
spintronics.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
topological insulator develops gaps in the Floquet-Bloch band spectrum
when illuminated with a circularly polarized laser. These Floquet-Bloch
bands are characterized by nontrivial Chern numbers which only depend on
the helicity of the polarization of the radiation field. Here we propose
a setup consisting of a pair of counterrotating lasers, and show that
one-dimensional chiral states emerge at the interface between the two
lasers. These interface states turn out to be spin polarized and may
trigger interesting applications in the field of optoelectronics and
spintronics.
Perez-Piskunow, P M; Torres, L E F Foa; Usaj, Gonzalo
Hierarchy of Floquet gaps and edge states for driven honeycomb lattices Journal Article
In: Physical Review A, vol. 91, no. 4, pp. 043625, 2015, ISSN: 1050-2947.
@article{ISI:000353121400005,
title = {Hierarchy of Floquet gaps and edge states for driven honeycomb lattices},
author = {P M Perez-Piskunow and L E F {Foa Torres} and Gonzalo Usaj},
doi = {10.1103/PhysRevA.91.043625},
issn = {1050-2947},
year = {2015},
date = {2015-04-01},
journal = {Physical Review A},
volume = {91},
number = {4},
pages = {043625},
abstract = {Electromagnetic driving in a honeycomb lattice can induce gaps and
topological edge states with a structure of increasing complexity as the
frequency of the driving lowers. While the high-frequency case is the
most simple to analyze we focus on the multiple photon processes allowed
in the low-frequency regime to unveil the hierarchy of Floquet edge
states. In the case of low intensities an analytical approach allows us
to derive effective Hamiltonians and address the topological character
of each gap in a constructive manner. At high intensities we obtain the
net number of edge states, given by the winding number, with a numerical
calculation of the Chern numbers of each Floquet band. Using these
methods, we find a hierarchy that resembles that of a Russian nesting
doll. This hierarchy classifies the gaps and the associated edge states
in different orders according to the electron-photon coupling strength.
For large driving intensities, we rely on the numerical calculation of
the winding number, illustrated in a map of topological phase
transitions. The hierarchy unveiled with the low-energy effective
Hamiltonians, along with the map of topological phase transitions,
discloses the complexity of the Floquet band structure in the
low-frequency regime. The proposed method for obtaining the effective
Hamiltonian can be easily adapted to other Dirac Hamiltonians of
two-dimensional Materials and even the surface of a three-dimensional
topological insulator.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
topological edge states with a structure of increasing complexity as the
frequency of the driving lowers. While the high-frequency case is the
most simple to analyze we focus on the multiple photon processes allowed
in the low-frequency regime to unveil the hierarchy of Floquet edge
states. In the case of low intensities an analytical approach allows us
to derive effective Hamiltonians and address the topological character
of each gap in a constructive manner. At high intensities we obtain the
net number of edge states, given by the winding number, with a numerical
calculation of the Chern numbers of each Floquet band. Using these
methods, we find a hierarchy that resembles that of a Russian nesting
doll. This hierarchy classifies the gaps and the associated edge states
in different orders according to the electron-photon coupling strength.
For large driving intensities, we rely on the numerical calculation of
the winding number, illustrated in a map of topological phase
transitions. The hierarchy unveiled with the low-energy effective
Hamiltonians, along with the map of topological phase transitions,
discloses the complexity of the Floquet band structure in the
low-frequency regime. The proposed method for obtaining the effective
Hamiltonian can be easily adapted to other Dirac Hamiltonians of
two-dimensional Materials and even the surface of a three-dimensional
topological insulator.
Lago, V Dal; Torres, L E F Foa
Line defects and quantum Hall plateaus in graphene Journal Article
In: Journal of Physics-Condensed Matter, vol. 27, no. 14, pp. 145303, 2015, ISSN: 0953-8984.
@article{ISI:000351738400005,
title = {Line defects and quantum Hall plateaus in graphene},
author = {V {Dal Lago} and L E F {Foa Torres}},
doi = {10.1088/0953-8984/27/14/145303},
issn = {0953-8984},
year = {2015},
date = {2015-04-01},
journal = {Journal of Physics-Condensed Matter},
volume = {27},
number = {14},
pages = {145303},
abstract = {Line defects in graphene can be either tailored-growth or arise
naturally and are at the center of many discussions. Here we study the
multiterminal conductance of graphene with an extended line defect in
the quantum Hall regime analyzing the effects of the geometry of the
setup, disorder and strain on the quantum Hall plateaus. We show that
the defect turns out to affect the local and non-local conductance in
very different ways depending on the geometrical configuration. When the
defect is parallel to the sample edges one gets an equivalent circuit
formed by parallel resistors. In contrast, when the defect bridges
opposite edges, the Hall conductance may remain unaltered depending on
the geometry of the voltage/current probes. The role of disorder, strain
and the microscopic details of the defect in our results is also
discussed. We show that the defect provides a realization of the
electrical analog of an optical beam splitter. Its peculiar energy
dependent inter-edge transmission allows it to be turned on or off at
will and it may be used for routing the chiral edge states.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
naturally and are at the center of many discussions. Here we study the
multiterminal conductance of graphene with an extended line defect in
the quantum Hall regime analyzing the effects of the geometry of the
setup, disorder and strain on the quantum Hall plateaus. We show that
the defect turns out to affect the local and non-local conductance in
very different ways depending on the geometrical configuration. When the
defect is parallel to the sample edges one gets an equivalent circuit
formed by parallel resistors. In contrast, when the defect bridges
opposite edges, the Hall conductance may remain unaltered depending on
the geometry of the voltage/current probes. The role of disorder, strain
and the microscopic details of the defect in our results is also
discussed. We show that the defect provides a realization of the
electrical analog of an optical beam splitter. Its peculiar energy
dependent inter-edge transmission allows it to be turned on or off at
will and it may be used for routing the chiral edge states.
2014
Torres, L E F Foa; Perez-Piskunow, P M; Balseiro, C A; Usaj, Gonzalo
Multiterminal Conductance of a Floquet Topological Insulator Journal Article
In: Physical Review Letters, vol. 113, no. 26, pp. 266801, 2014, ISSN: 0031-9007.
@article{ISI:000346836900008,
title = {Multiterminal Conductance of a Floquet Topological Insulator},
author = {L E F {Foa Torres} and P M Perez-Piskunow and C A Balseiro and Gonzalo Usaj},
url = {https://ri.conicet.gov.ar/bitstream/handle/11336/31800/CONICET_Digital_Nro.d43d95e3-2abd-4a55-a56b-8a48ac31e686_A.pdf?sequence=2\&isAllowed=y},
doi = {10.1103/PhysRevLett.113.266801},
issn = {0031-9007},
year = {2014},
date = {2014-12-01},
journal = {Physical Review Letters},
volume = {113},
number = {26},
pages = {266801},
abstract = {We report on simulations of the dc conductance and quantum Hall response
of a Floquet topological insulator using Floquet scattering theory. Our
results reveal that laser-induced edge states lead to quantum Hall
plateaus once imperfect matching with the nonilluminated leads is
lessened. The magnitude of the Hall plateaus, however, is not directly
related to the number and chirality of all the edge states at a given
energy, as usual. Instead, the plateaus are dominated by those edge
states adding to the time-averaged density of states. Therefore, the dc
quantum Hall conductance of a Floquet topological insulator is not
directly linked to topological invariants of the full Floquet bands.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
of a Floquet topological insulator using Floquet scattering theory. Our
results reveal that laser-induced edge states lead to quantum Hall
plateaus once imperfect matching with the nonilluminated leads is
lessened. The magnitude of the Hall plateaus, however, is not directly
related to the number and chirality of all the edge states at a given
energy, as usual. Instead, the plateaus are dominated by those edge
states adding to the time-averaged density of states. Therefore, the dc
quantum Hall conductance of a Floquet topological insulator is not
directly linked to topological invariants of the full Floquet bands.
Usaj, Gonzalo; Perez-Piskunow, P M; Torres, L E F Foa; Balseiro, C A
Irradiated graphene as a tunable Floquet topological insulator Journal Article
In: Physical Review B, vol. 90, no. 11, pp. 115423, 2014, ISSN: 1098-0121.
@article{ISI:000342159000003,
title = {Irradiated graphene as a tunable Floquet topological insulator},
author = {Gonzalo Usaj and P M Perez-Piskunow and L E F {Foa Torres} and C A Balseiro},
url = {https://ri.conicet.gov.ar/bitstream/handle/11336/31852/CONICET_Digital_Nro.27f6decb-79ac-482b-bed6-a1656c3987a9_A.pdf?sequence=2\&isAllowed=y},
doi = {10.1103/PhysRevB.90.115423},
issn = {1098-0121},
year = {2014},
date = {2014-09-01},
journal = {Physical Review B},
volume = {90},
number = {11},
pages = {115423},
abstract = {In the presence of a circularly polarized mid-infrared radiation
graphene develops dynamical band gaps in its quasienergy band structure
and becomes a Floquet insulator. Here, we analyze how topologically
protected edge states arise inside these gaps in the presence of an
edge. Our results show that the gap appearing at h Omega/2, where h
Omega is the photon energy, is bridged by two chiral edge states whose
propagation direction is set by the direction of the polarization of the
radiation field. Therefore, both the propagation direction and the
energy window where the states appear can be controlled externally. We
present both analytical and numerical calculations that fully
characterize these states. This is complemented by simple topological
arguments that account for them and by numerical calculations for the
case of the semi-infinite sample, thereby eliminating finite-size
effects.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
graphene develops dynamical band gaps in its quasienergy band structure
and becomes a Floquet insulator. Here, we analyze how topologically
protected edge states arise inside these gaps in the presence of an
edge. Our results show that the gap appearing at h Omega/2, where h
Omega is the photon energy, is bridged by two chiral edge states whose
propagation direction is set by the direction of the polarization of the
radiation field. Therefore, both the propagation direction and the
energy window where the states appear can be controlled externally. We
present both analytical and numerical calculations that fully
characterize these states. This is complemented by simple topological
arguments that account for them and by numerical calculations for the
case of the semi-infinite sample, thereby eliminating finite-size
effects.
Bracamonte, M V; Lacconi, G I; Urreta, S E; Torres, L E F Foa
On the Nature of Defects in Liquid-Phase Exfoliated Graphene Journal Article
In: Journal of Physical Chemistry C, vol. 118, no. 28, pp. 15455-15459, 2014, ISSN: 1932-7447.
@article{ISI:000339368700041,
title = {On the Nature of Defects in Liquid-Phase Exfoliated Graphene},
author = {M V Bracamonte and G I Lacconi and S E Urreta and L E F {Foa Torres}},
doi = {10.1021/jp501930a},
issn = {1932-7447},
year = {2014},
date = {2014-07-01},
journal = {Journal of Physical Chemistry C},
volume = {118},
number = {28},
pages = {15455-15459},
abstract = {Liquid-phase exfoliation is one of the most promising routes for
large-scale production of multilayer graphene dispersions. These
dispersions, which may be used in coatings, composites, or paints, are
believed to contain disorder-free graphene multilayers. Here, we address
the nature of defects in such samples obtained by liquid-phase
exfoliation of graphite powder in N-methyl-2-pyrrolidone. Our Raman
spectroscopy data challenge the assumption that these multilayers are
free of bulk defects, revealing that defect localization strongly
depends on the sonication time. For short ultrasound times, defects are
located mainly at the layer edges but they turn out to build up in the
bulk for ultrasonic times above 2 h. This knowledge may help to devise
better strategies to achieve high-quality graphene dispersions.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
large-scale production of multilayer graphene dispersions. These
dispersions, which may be used in coatings, composites, or paints, are
believed to contain disorder-free graphene multilayers. Here, we address
the nature of defects in such samples obtained by liquid-phase
exfoliation of graphite powder in N-methyl-2-pyrrolidone. Our Raman
spectroscopy data challenge the assumption that these multilayers are
free of bulk defects, revealing that defect localization strongly
depends on the sonication time. For short ultrasound times, defects are
located mainly at the layer edges but they turn out to build up in the
bulk for ultrasonic times above 2 h. This knowledge may help to devise
better strategies to achieve high-quality graphene dispersions.
Ramos, J P; Torres, L E F Foa; Orellana, P A; Apel, V M
Single-parameter spin-pumping in driven metallic rings with spin-orbit coupling Journal Article
In: Journal of Applied Physics, vol. 115, no. 12, pp. 124507, 2014, ISSN: 0021-8979.
@article{ISI:000333901100090,
title = {Single-parameter spin-pumping in driven metallic rings with spin-orbit coupling},
author = {J P Ramos and L E F {Foa Torres} and P A Orellana and V M Apel},
doi = {10.1063/1.4868902},
issn = {0021-8979},
year = {2014},
date = {2014-03-01},
journal = {Journal of Applied Physics},
volume = {115},
number = {12},
pages = {124507},
abstract = {We consider the generation of a pure spin-current at zero bias voltage
with a single time-dependent potential. To such end we study a device
made of a mesoscopic ring connected to electrodes and clarify the
interplay between a magnetic flux, spin-orbit coupling, and
non-adiabatic driving in the production of a spin and electrical
current. By using Floquet theory, we show that the generated spin to
charge current ratio can be controlled by tuning the spin-orbit
coupling. (C) 2014 AIP Publishing LLC.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
with a single time-dependent potential. To such end we study a device
made of a mesoscopic ring connected to electrodes and clarify the
interplay between a magnetic flux, spin-orbit coupling, and
non-adiabatic driving in the production of a spin and electrical
current. By using Floquet theory, we show that the generated spin to
charge current ratio can be controlled by tuning the spin-orbit
coupling. (C) 2014 AIP Publishing LLC.
Perez-Piskunow, P M; Usaj, Gonzalo; Balseiro, C A; Torres, L E F Foa
Floquet chiral edge states in graphene Journal Article
In: Physical Review B, vol. 89, no. 12, pp. 121401, 2014, ISSN: 1098-0121.
@article{ISI:000332456000001,
title = {Floquet chiral edge states in graphene},
author = {P M Perez-Piskunow and Gonzalo Usaj and C A Balseiro and L E F Foa Torres},
url = {https://ri.conicet.gov.ar/bitstream/handle/11336/27548/CONICET_Digital_Nro.ad91487c-974f-44c4-a660-13f320b80798_A.pdf?sequence=2\&isAllowed=y},
doi = {10.1103/PhysRevB.89.121401},
issn = {1098-0121},
year = {2014},
date = {2014-03-01},
journal = {Physical Review B},
volume = {89},
number = {12},
pages = {121401},
abstract = {We report on the emergence of laser-induced chiral edge states in
graphene ribbons. Insights on the nature of these Floquet states is
provided by an analytical solution which is complemented with numerical
simulations of the transport properties. Guided by these results we show
that graphene can be used for realizing nonequilibrium topological
states with striking tunability: while the laser intensity can be used
to control their velocity and decay length, changing the laser
polarization switches their propagation direction.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
graphene ribbons. Insights on the nature of these Floquet states is
provided by an analytical solution which is complemented with numerical
simulations of the transport properties. Guided by these results we show
that graphene can be used for realizing nonequilibrium topological
states with striking tunability: while the laser intensity can be used
to control their velocity and decay length, changing the laser
polarization switches their propagation direction.
Torres, L E F Foa; Roche, S; Charlier, J C
Introduction to Graphene-Based Nanomaterials: From Electronic Structure to Quantum Transport Book
Cambridge University Press, 2014, ISBN: 9781107030831.
BibTeX | Links:
@book{foa_torres_introduction_2014,
title = {Introduction to Graphene-Based Nanomaterials: From Electronic Structure to Quantum Transport},
author = {L E F {Foa Torres} and S Roche and J C Charlier},
url = {http://www.cambridge.org/9781107030831},
isbn = {9781107030831},
year = {2014},
date = {2014-01-01},
publisher = {Cambridge University Press},
keywords = {},
pubstate = {published},
tppubtype = {book}
}
2013
Ingaramo, Lucas H; Torres, Luis E F Foa
Quantum charge pumping in graphene-based devices: When lattice defects do help Journal Article
In: Applied Physics Letters, vol. 103, no. 12, pp. 123508, 2013, ISSN: 0003-6951.
@article{ISI:000324826000083,
title = {Quantum charge pumping in graphene-based devices: When lattice defects do help},
author = {Lucas H Ingaramo and Luis E F {Foa Torres}},
doi = {10.1063/1.4821262},
issn = {0003-6951},
year = {2013},
date = {2013-09-01},
journal = {Applied Physics Letters},
volume = {103},
number = {12},
pages = {123508},
abstract = {Quantum charge pumping, the quantum coherent generation of a dc current
at zero bias through time-dependent potentials, provides outstanding
opportunities for metrology and the development of nanodevices. The long
electronic coherence times and high quality of the crystal structure of
graphene may provide suitable building blocks for such quantum pumps.
Here, we focus in adiabatic quantum pumping through graphene nanoribbons
in the Fabry-Perot regime highlighting the crucial role of defects by
using atomistic simulations. We show that even a single defect added to
the pristine structure may produce a two orders of magnitude increase in
the pumped charge. (C) 2013 AIP Publishing LLC.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
at zero bias through time-dependent potentials, provides outstanding
opportunities for metrology and the development of nanodevices. The long
electronic coherence times and high quality of the crystal structure of
graphene may provide suitable building blocks for such quantum pumps.
Here, we focus in adiabatic quantum pumping through graphene nanoribbons
in the Fabry-Perot regime highlighting the crucial role of defects by
using atomistic simulations. We show that even a single defect added to
the pristine structure may produce a two orders of magnitude increase in
the pumped charge. (C) 2013 AIP Publishing LLC.
Calvo, Hernan L; Perez-Piskunow, Pablo M; Pastawski, Horacio M; Roche, Stephan; Torres, Luis E F Foa
Non-perturbative effects of laser illumination on the electrical properties of graphene nanoribbons Journal Article
In: Journal of Physics-Condensed Matter, vol. 25, no. 14, pp. 144202, 2013, ISSN: 0953-8984, (Invited Article).
@article{ISI:000316210200005,
title = {Non-perturbative effects of laser illumination on the electrical properties of graphene nanoribbons},
author = {Hernan L Calvo and Pablo M Perez-Piskunow and Horacio M Pastawski and Stephan Roche and Luis E F {Foa Torres}},
doi = {10.1088/0953-8984/25/14/144202},
issn = {0953-8984},
year = {2013},
date = {2013-04-01},
journal = {Journal of Physics-Condensed Matter},
volume = {25},
number = {14},
pages = {144202},
abstract = {Floquet theory combined with a realistic description of the electronic
structure of illuminated graphene and graphene nanoribbons is developed
to assess the emergent non-adiabatic and non-perturbative effects on the
electronic properties. Here we introduce an efficient computational
scheme and illustrate its use by applying it to graphene nanoribbons in
the presence of both linear and circular polarization. The interplay
between confinement due to the finite sample size and laser-induced
transitions is shown to lead to sharp features in the average
conductance and density of states. Particular emphasis is given to the
emergence of the bulk limit response.},
note = {Invited Article},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
structure of illuminated graphene and graphene nanoribbons is developed
to assess the emergent non-adiabatic and non-perturbative effects on the
electronic properties. Here we introduce an efficient computational
scheme and illustrate its use by applying it to graphene nanoribbons in
the presence of both linear and circular polarization. The interplay
between confinement due to the finite sample size and laser-induced
transitions is shown to lead to sharp features in the average
conductance and density of states. Particular emphasis is given to the
emergence of the bulk limit response.
Calvo, Hernán L; Pastawski, Horacio M; Roche, Stephan; Torres, Foa
On the Possibility of Observing Tunable Laser-Induced Bandgaps in Graphene Book Chapter
In: Graphene, Carbon Nanotubes, and Nanostructures, 2013.
@inbook{calvo_possibility_2013,
title = {On the Possibility of Observing Tunable Laser-Induced Bandgaps in Graphene},
author = {Hern\'{a}n L Calvo and Horacio M Pastawski and Stephan Roche and Foa Torres},
url = {https://www.taylorfrancis.com/},
doi = {10.1201/b13905-3},
year = {2013},
date = {2013-01-01},
urldate = {2020-08-08},
booktitle = {Graphene, Carbon Nanotubes, and Nanostructures},
abstract = {This chapter focuses on the interplay between optical and electronic properties, and addresses the issue of tunability of the latter using a laser field.},
keywords = {},
pubstate = {published},
tppubtype = {inbook}
}