Multiple Hall Effects in Functionalized Bismuth Monolayers*

Advances in (quantum) spin and anomalous Hall effect, as well as (anomalous) valley Hall effect suggest the electronic degrees of freedom (spin, charge, and valley) can be used as different information carriers [1,2]. The realization of multiple Hall effects in a single 2D material provides a fascinating opportunity to manipulate the implementation of such information [3]. Motivated by the experiments [4], we combine a tight-binding model with first-principles calculations to reveal that with a large nontrivial gap, quantum spin Hall effects (QSHEs) and valley Hall effects appear simultaneously in the functionalized bismuth monolayers [5]. A staggered exchange field is introduced to realize the spin-valley polarized QSHEs. With gate control, QSHE and anomalous charge, spin, valley Hall effects can be observed in the single system [5]. These predicted multiple Hall effects could enable applications of the functionalized bismuth monolayers in electronics, spintronics, and valleytronics.
[1] M. Hasan, et. al., RMP 82, 3045 (2010).
[2] D. Xiao, et. al., RMP 82, 1959 (2010).
[3] T. Zhou, et. al., PRB 94, 235449 (2016).
[4] F. Reis, et al., Science 357, 287 (2017).
[5] T. Zhou, et. al., npj Quant. Mater. 3, 39 (2018).