Influence of a Parallel Magnetic Field on the Microwave-Induced Resistance and Photovoltaic Oscillations

Microwave induced photovoltaic (PV) and resistance oscillations (MIRO) were studied in high-mobility ($\mu >$ 8$\times $10$^{6}$ cm$^{2}$/V s) 2D electron gas in GaAs/Al$_{x}$Ga$_{1-x}$As Hall bar samples employing a two-axis magnet system (perpendicular field B$_{\bot }$ and parallel field B//). Consistent with the previous results, strong MIRO were observed and were found to diminish under a B// $\sim $ 1 T. We observed two types of PV oscillations: 1) PV oscillations that are periodic in 1/B$_{\bot }$, with a periodicity similar to MIRO, but are anti-symmetric with respect to B$_{\bot }$ = 0; and, 2) PV oscillations due to edge magnetoplasmon modes, which are periodic in B$_{\bot }$ and are symmetric with respect to B$_{\bot }$ = 0. Characteristically, the 1/B$_{\bot }$ oscillations in PV were completely suppressed by a B// $\sim $ 1 T, whereas the B$_{\bot }$-periodic oscillations retain their main features even in B// = 2 T. Experimental data and a brief discussion will be presented. The work at Rice was supported by NSF DMR-0706634.