Facultad de Ciencias

Seminario: "Chirality in Moiré systems"

Ponente

Profesores Tobias Stauber y Guillermo Gómez Santos

Institución de origen

Departamento de Física de la Materia Condensada

Fecha

15-10-2021

Hora

12:00 h

Lugar

Evento online, MS-TEAMS, “Seminarios del Departamento”

Descripción

Twisted bilayer graphene has attracted much attention due to its novel electronic properties that arise in the flat band regime at the magic angle [1] [2] After a brief
introduction, we will present our recent theoretical results on the inherent chirality of the system.

In particular, we will show that the Moiré structure of TBG leads to a paramagnetic response and chiral plasmons which are accommodated by a longitudinal magnetic moment [3] This unusual response also leads to an emergent magnetic texture when the system is driven out of equilibrium [4].

The real space chirality of twisted bilayer graphene can be characterized by a simple formula and we observe a sign change due to an emergent C [6] symmetry Surprisingly, this change occurs in the flat band regime and thus offers a new definition of the magic angle based on a macroscopic observable which is accessible in typical transport experiments [5]

We finally predict an unprecedented large local chirality for the plasmonic near field if the twist angle is slightly away from the magic angle Twisted bilayer graphene or other Moiré heterostructure should thus provide a novel platform for chiral cavities that might be even able to catalyze the reaction of new chiral molecules while conserving time reversal symmetry [6]

[1] Y. Cao , V. Fatemi , A. Demir, S. Fang , Spencer L. Tomarken, Jason Y. Luo , J. D. Sanchez Yamagishi , K. Watanabe , T. Taniguchi , E. Kaxiras , R. C. Ashoori & P. Jarillo Herrero , Nature 556 , 80 (2018)
[2] Y. Cao , V. Fatemi , S. Fang , K. Watanabe , T. Taniguchi , E. Kaxiras , and P. Jarillo Herrero, Nature 556 , 43 (2018)
[3] T. Stauber , T. Low , and G. Gómez Santos, Phys . Rev. Lett . 120 , 046801 (2018); Phys . Rev. B 98 , 195414 (2018)
[4] D. Bahamon , G. Gómez Santos, T.Stauber , Nanoscale 12 , 15383 (2020)
[5] T Stauber J González, and G Gómez Santos, Phys Rev B 102 081404 (2020)
[6] T. Stauber ., T. Low , and G. Gómez Santos, Nano Letters 20 , 8711 (2020)

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