Current scaling of the resistance peaks in the microwave radiation induced magnetoresistance oscillations

We examine the size-dependence of microwave photo-excited transport in the high mobility GaAs/AlGaAs system over the temperature range 0.3 ≤ T ≤ 1.2K, in nominally identical Hall bar specimens with a length (L) to width (W) ratio L/W = 1, for different W. We report size dependent characteristics such as a strong W-dependence of the photoexcited magnetoresistive response, with a stronger response generally observable at larger W. In addition, we examine, in detail, the change in response observed under a I_DC current bias at the photo-excited oscillatory magnetoresistive peaks, especially when the I_DC also produces an overall giant magnetoresistance. We demonstrate here a ”universality” in the decay of the photoexcited oscillatory magnetoresistance peak height over the examined temperatures, sizes, and applied I_DC. The results suggest that the photoexcited resistance maxima scale with the current density j = I/W rather than I, and indicate that, the bulk current is maintained at the photo-excited magnetoresistive peaks in the photo-excited 2DES. On the other hand, at the oscillatory resistance minima, the minima depth is generally insensitive to I_DC.