Unique signatures of the Rashba effect in the magneto-optical properties of two-dimensional semiconductors

We have shown theoretically that giant magnetic circular dichroism (MCD) should be observed at the absorption band edge of two-dimensional (2D) semiconductors exhibiting Rashba splitting in the presence of a magnetic field perpendicular to the 2D layers. This feature has been found in calculated interband sigma+ and sigma- light absorption coefficients for transitions between the Landau levels (LLs) of the conduction and valence bands. The giant MCD signal is shown to be connected with an unusual magnetic field dependence of the lowest LL in the presence of the Rashba term. A second unique signature of Rashba splitting is a reduction of the exciton diamagnetic shift created by the Rashba terms. We show that these terms lead to the characteristic Rashba exciton dispersion with minima at nonzero momentum. The analysis of the exciton dispersion at nonzero momentum conducted by Gor'kov and Dzaloshinskii shows that variable separation leads to mixed magneto-impulse terms. These terms lead to a negative diamagnetic shift, which should be observed in the exciton photoluminescence that occurs from the dispersion minimum.