Electron spin resonance on a two-dimensional electron gas in a single AlAs quantum well

Direct electron spin resonance (ESR) on a high mobility two-dimensional electron gas in a single AlAs quantum well reveals an electronic g factor of 1.991 at 9.35 GHz and 1.989 at 34 GHz with a minimum linewidth of 7 G. The ESR amplitude and its temperature dependence suggest that the signal originates from the effective magnetic field caused by the spin-orbit interaction and a modulation of the electron wave vector caused by the microwave electric field. This contrasts markedly with conventional ESR that detects through the microwave magnetic field.