Microwave photoexcited transport in the GaAs/AlGaAs 2D electron system in the regime of the photo-excited zero-resistance states

The high mobility GaAs/AlGaAs system demonstrated the possibility of realizing the microwave radiation induced zero-resistance states in the diagonal resistance of the 2DES without concurrent Hall quantization, in the vicinity of B_j = 4/(4j+1)B_f, where B_f = 2πfm*/e, upon microwave photo-excitation of the 2DES in a small perpendicular magnetic field at liquid helium temperatures. We examine here associated transport phenomena under microwave excitation and also under the influence of a supplementary dc-current-bias. Our previous studies have shown that a dc- current biasing of the high mobility 2DES provides leads to a dc-current tunable giant magnetoresistance (GMR) in the presence of 100’s-of-millitesla-type magnetic fields. Indeed, the magnetoresistance was shown to progressively change from positive to negative with increasing I_dc, yielding negative giant-magnetoresistance at the lowest temperature and highest I_dc. In this study, we examine the interplay between the microwave induced oscillatory resistance and the current induced GMR in the GaAs/AlGaAs system at millikelvin temperatures to identify some striking correlations.