QDev Seminar: Georg Wolfgang Winkler

Effects of the electrostatic environment on the g-factor in Majorana nanowires

The g-factor of the Andreev bound states in a Majorana device determine the critical magnetic field at which a Majorana zero mode forms. Recent experiments show that the g-factor in the nanowire has a strong dependence on the backgate voltage. We perform simulations of a realistic Majorana nanowire device, strongly proximitized by Al, including electrostatics and the orbital effect of magnetic field. We find two effects responsible for the gate voltage dependence of the g-factor. The first being, that the coupling to the superconductor, which renormalizes the semiconductor g-factor, depends on gate voltage. The second effect is related to the orbital enhancement of g-factor which is suppressed by large negative gate voltages. Our results help in understanding the interplay of electrostatics, proximity coupling to superconductor and the orbital effect of magnetic field in Majorana nanowire devices and provide guidelines to which regimes are favorable in experiments.