Control of the spin-orbit coupling by gate voltage in semiconductor FET structures

We demonstrate that the strength of the spin-orbit (SO) coupling can be controlled systematically by gate voltage (VG) in HgCdTe FET structures. This indicates that the Rashba effect can be controlled by the external bias. The strength of the SO coupling is estimated from the weak antilocalization(WAL) effect. The experimental data are fitted by using the D'yakonov-Perel (DP) mechanism, and the SO coupling strength is much larger than those of other materials. This strong Rashba effect is an unique feature of HgCdTe FET, which originates from both strong intrinsic SO coupling of HgCdTe and high structural inversion asymmetry of our device. It provides a great advantage over other materials for spin manipulation in semiconductor spin devices.