Elementary electronic excitation from a two-dimensional hole gas in the presence of spin-orbit interaction

We present a theoretical study of the elementary electronic excitation associated with plasmon modes in a two-dimensional hole gas (2DHG) in the presence of spin-orbit (SO) interaction induced by the Rashba effect, The calculation is carried out using a standard random-phase-approximation approach. It is found that, in such a spintronic system, plasmon excitation can be achieved via intra- and inter-SO electronic transitions around the Fermi level. As a result, the intra- and inter-SO plasmon modes can be observed. More importantly, the plasmon modes induced by inter-SO transition are optic-like and these modes can be directly applied to identify the Rashba spin splitting in 2DHG systems through optical measurements. The interesting features of the plasmon excitation in a spin-split 2DHG are analysed and discussed in detail. Moreover, the results obtained for a 2DHG arc compared with those obtained for a spin-splitting 2DEG reported very recently.