arXiv:1002.2851v1 [cond-mat.mes-hall] 15 Feb 2010 1 We present a theoretical study of magnetoplasmon spectrum of a two-dimensional electron gas in the presence of Rashba spin-orbit interaction (RSOI), one-dimensional weak electric modulation and a perpendicular magnetic field. The intra-Landau-band magnetoplasmon spectrum is deter- mined in the presence of spin-orbit interaction within the self consistent field approach at finite temperature. Due to Rashba effect, the spin of finite-momentum electrons feels a magnetic field perpendicular to the electron momentum in the inversion plane. The magnetoplasmon spectrum of the modulated two-dimensional electron gas (M2DEG) system is found to exhibit beating of Weiss oscillations due to Rashba effect which is the focus of this work. This effect is absent in the magnetoplasmon spectrum of M2DEG if Rashba spin-orbit interaction is not taken into account. In addition, our finite temperature theory ficilitates analysis of effects of temperature on the mag- netoplasmon spectrum of M2DEG in the presence of RSOI. We find that the beating pattern is damped but continues to persist at a finite but low temperature. Abstract Spin-orbit interaction effects on the magnetoplasmon spectrum of modulated two-dimensional electron gas M. Tahir ∗ Department of Physics, University of Sargodha, Sargodha 40100, Pakistan. K. Sabeeh † Department of Physics, Quaid-i-Azam University Islamabad 45320, Pakistan. (Date textdate; Received textdate; Revised textdate; Accepted textdate; Published textdate)