Extended Data Fig. 7: Three-dimensional illustration of particle–hole asymmetric Rashba bands in BAs with B = 15 T.
From: Rashba valleys and quantum Hall states in few-layer black arsenic
a, The spin–valley-flavoured Rashba bands in the VB of QL BAs. b, The Γ Rashba bands in the CB of QL BAs. The three-dimensional band structures of QL BAs are based on the calculation results in Extended Data Fig. 3 (Ez = 0.3 V nm−1). For the 2DHG, low, negative Vg creates two single-flavoured FSs with τzsz = 1, whereas high, negative Vg leads to the formation of inner–outer-nested FSs when EF intersects oppositely flavoured spin channels. For the 2DEG, the FS topology is dependent on the relative position of EF to the Zeeman energy gap ES. Note that the high in-plane band anisotropy in BAs has profound effects on the D± Rashba formation, by pushing py orbitals to much higher energy. Without the unique puckering square lattice, the D± valley would split into helical inner–outer Rashba bands centring on X. For the 2DEG, we can also see the square lattice warping of the Γ Rashba bands.
