Manipulating Giant Rashba Valley Splitting and Quantum Hall States in Few-Layer Black Arsenic by Electrostatic Gating

Abstract

Exciting phenomena may emerge in non-centrosymmetric two-dimensional (2D) electronic systems when spin-orbit coupling (SOC) interplays dynamically with Coulomb interactions, band topology, and external modulating forces, etc. Here, we report illuminating synergetic effects between SOC and Stark in centrosymmetric few-layer black arsenic (BAs), manifested as giant Rashba valley splitting and exotic quantum Hall states (QHS) reversibly controlled by electrostatic gating. The unusual finding is rooted in the puckering square lattice of BAs, in which heavy $4p$ orbitals form highly asymmetric $\Gamma$ valley with the $p_z$ symmetry and $D$ valleys of the $p_x$ origin, located at the Brillouin zone (BZ) center and near the time reversal invariant momenta of $X$, respectively. When the structure inversion symmetry is broken by perpendicular electric field, giant Rashba SOC is activated for the $p_x$ bands to produce strong spin-polarized $D^{+}$ and $D^{-}$ valleys related by time-reversal symmetry, coexisting with weak $\Gamma$ Rashba bands constrained by the $p_z$ symmetry. Intriguingly, strong Stark effect shows the same $p_x$-orbital selectiveness for $D$, collectively shifting the valence band maximum of $D^{\pm }$ valleys to exceed the $\Gamma$ pockets. Such an orchestrating effect between SOC and Stark allows us to realize gate-tunable spin valley manipulations for 2D hole gas, as revealed by unconventional magnetic field triggered even-to-odd transitions in QHS. For electron doping, the quantization of the $\Gamma$ Rashba bands is characterized by peculiar density-dependent transitions in band topology from two parabolic valleys to a unique inner-outer helical structure when charge carrier concentrations increase.

9 pages, 4 figures

References in corpus (7)

• Quantum Spin Hall Effect and Topological Phase Transition in HgTe Quantum Wells
• Observation of topological surface state quantum Hall effect in an intrinsic three-dimensional topological insulator
• Fast pick up technique for high quality heterostructures of bilayer graphene and hexagonal boron nitride
• Unconventional Quantum Hall Effect and Tunable Spin Hall Effect in MoS2 Trilayers
• Defects controlled hole doping and multi-valley transport in SnSe single crystals
• Rashba-like spin splitting along three momentum directions in trigonal layered PtBi2
• Odd-integer quantum Hall states and giant spin susceptibility in p-type few-layer WSe2

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• Atomically thin obstructed atomic insulators with robust edge modes and quantized spin Hall effect
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