Saskia Fischer: Topological Surface States and Two-Dimensional Layered Transport in bulk Bi2Se3

Helically spin-polarized Dirac fermions in topologically protected surface states are of high interest as a new state of quantum matter and they are studied in so-called topological insulators (TI). However, we found that in a prototypical three-dimensional TI material, Bi2Se3, the magneto-transport experiments indicate that these surface states may coexist with a layered two-dimensional electron system in the bulk [1]. Recently, we demonstrated quantization effects in the Hall resistance at temperatures up to 50 K in nominally undoped bulk Bi2Se3 single crystals with a high electron density (n ~ 2·1019 cm−3). From the angular and temperature dependence of the Hall resistance and the Shubnikov-de Haas oscillations we identify 3D and 2D contributions to transport. Angular resolved photoemission spectroscopy proves the existence of TSS. Here, I will outline a model for Bi2Se3 and suggest that the coexistence of TSS and 2D layered transport may stabilize the quantum oscillations of the Hall resistance.

[1] O. Chiatti et al., Scientific Reports 6, 27483 (2016).

[2] M. Busch et al., Scientific Reports 8, 485(2018).