A theoretical study of the collective excitation associated with plasmon modes is presented for a two-dimensional electron gas in the presence of spin orbit (SO) interaction induced by the Rashba effect. In such a case, the plasmon excitation can be achieved via intra- and inter-SO electronic transitions. As a result, three branches of the plasmon oscillations can be observed. It is found that inter-SO plasmons depend strongly on sample parameters and, at a long-wavelength limit, are optic-like, in contrast to intra-SO ones. The interesting features of these plasmon modes are examined.The author is a Research Fellow of the Australian Research
Council. Discussions with P. Vasilopoulos (Concordia,
Canada) and M. P. Das (ANU, Australia) are gratefully
acknowledged
