Optical spectrum of a spin-split two-dimensional electron gas

In this paper, we examine how spin-orbit interaction induced by the Rashba effect affects the optical spectrum of a two-dimensional electron gas (2DEG). The calculation is carried out on the basis of a standard random-phase approximation for electron-electron interaction. It is found that for a spin-split 2DEG, the spectrum of optical absorption depends strongly on two opticlike plasmon modes caused by inter-spin-orbit excitation. More interestingly, we find that the position and the width of the spectrum relate directly to important spintronic properties. From these theoretical findings, we propose that the Rashba spin splitting can be identified optically and important spintronic coefficients of a 2DEG can be measured via optical experiments.