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Título:: Tatiana Rappoport (UFRJ): Electronic Properties of Bismuthene
quando:: 06.09.2018 11.00 h
onde:: Sala de seminário, 5o andar da Torre Nova -
Categoria:: Seminários

Descrição

Seminário de Matéria Condensada

06/09 - 5a feira - 11h00

Sala 528 - 5o andar da torre nova (Atenção para a mudança de sala)

Palestrante: Tatiana G. Rappoport, (UFRJ)

Título: Electronic Properties of Bismuthene

Resumo:
In recent years, topological insulators have caught the attention of the condensed matter physics community, due to their exotic properties and potential applications. 2D topological insulators, also known as quantum spin hall insulators (QSHI), have edge states that are extremely robust against disorder because the only available backscattering channel is forbidden by topology. Consequently they are good candidates for the development of a next generation of electronic and spintronic devices.

One possible route to obtain QSHIs with large band-gaps is the search for 2D materials where the electronic structure can be modeled by a px-py honeycomb Hamiltonian. In this case, the band structure also presents a Dirac cone similar to their pz counterpart, accompanied by two extra narrow bands symmetrically located at low and high energies. When the spin-orbit coupling is taken into account, the band structure presents three topological gaps that have sizes of the order of the atomic level splitting. This model has been previously studied in the context of optical lattices [1].

Recently Reis et al. reported the realization of a condensed matter analogue of px-py honeycomb systems in flat bismuthene[2]. They used a SiC substrate to grow a planar bismuth layer, in which the substrate helps the stabilization of bismuthene and serves as an orbital filtering platform. This approach can be seen as a new paradigm to produce QSHI with large gaps, where the orbital properties of the system are tuned by conveniently choosing a substrate.

Motivated by these results, we consider a minimal model that consists of a px-py honeycomb lattice with spin-orbit coupling. We perform a systematic analysis of the influence of the π-bonding in the band structure, as its strength depends on both material and substrate. In addition to this, we perform quantum transport calculations in presence of Anderson disorder and vacancies and analyze the robustness of the topological gaps against disorder and Rashba spin-orbit coupling.

[1] C. Wu, Phys. Rev. Lett. 101, 186807 (2008)

[2] F. Reis, G. Li, L. Dudy, M. Bauernfeind, S. Glass, W. Hanke, R. Thomale, J. Scha ̈fer, and R. Claessen, Science 357, 287 (2017)