Controlling anisotropic surface group velocity and effective mass in topological crystalline insulator SnTe by Rashba effect

Abstract Rashba effect has become important in the realization of exotic topological features. Herein, we theoretically investigate the Rashba spin–orbit coupling (RSOC) effects on the dispersion energy, group velocity (GV) and effective mass (EM) of Dirac fermions in the topological crystalline insulator SnTe (001) surface. We found that different classes of RSOCs do not change the qualitative behavior of the band structure; its main effect is to break the symmetry of the gapless bands down to a group of discrete rotations and to slightly shift the phase boundaries. Moreover, the inherent anisotropic surface features hold with RSOC. The modulation mechanism of RSOC effects is further analyzed from the orientation-dependent GV and EM at different RSOC values. It is found that the GV and EM of fermions are band-dependent and symmetric concerning the RSOC sign, which plays a decisive role in modifying the optical properties. Our study provides new insight into the designing nanodevices for electric-field-controllable topological electronics.