Gate control of the giant Rashba effect in HgTe quantum wells

HgTe/Hg0.3Cd0.7Te(001) quantum well structures fabricated with a Si-O-N insulator layer and an Au top gate electrode exhibit hysteresis effects in their gate-voltage dependent carrier density and thus a nonlinear variation of the Rashba spin-orbit splitting energy (AR), Charging and discharging of states at the semiconductor insulator interface has been found to be responsible for this effect. The quantitative agreement with a simple capacitor model has been used to identify the maximum hysteresis-free gate-voltage range. A nearly linear variation Of AR with applied gate voltage has been observed in this range.