Demonstration of a 1/4-cycle phase shift in the radiation-induced oscillatory magnetoresistance in GaAs/AlGaAs devices

We examine the phase and the period of the radiation-induced oscillatory magnetoresistance in GaAs/AlGaAs devices utilizing in situ magnetic field calibration by electron spin resonance of diphenyl-picryl-hydrazal. The results confirm a f-independent 1/4-cycle phase shift with respect to the hf = j (h) over bar omega(c) condition for j greater than or equal to 1, and they also suggest a small (approximate to2%) reduction in the effective mass ratio, m*/m, with respect to the standard value for GaAs/AlGaAs devices.