Study of the inelastic length under microwave photo-excitation in the GaAs/AlGaAs 2D electron system

Magnetotransport measurements in ultra-high mobility GaAs/AlGaAs 2D electron systems (2DES) exhibit a narrow negative magnetoresistance (MR) effect around the null magnetic field, which is similar in appearance to the well-known weak localization (WL) effect in metals, semiconductors, etc. However, the origin of WL-like effect in high mobility GaAs/AlGaAs 2DES specimens is still under debate. In this experimental work, the results exhibit that the incident microwave (MW) significantly modifies the observed narrow negative-MR feature, such that the WL-like peaks disappear at high power regime. This study aims to examine the influence of MW power on the WL-like effect. Thus, the observed negative-MR data were fit using 2D WL model by Hikami et al., to extract the characteristic inelastic length (l_i) as a function of MW power [1]. Results suggest that the fit extracted l_i is reduced by 50% upon increasing the MW power up to 2 mW. Further analysis of the data suggest that MW induced electron heating is partly responsible for the observed reduction in the l_i under photo-excitation.
1. S. Hikami, et. al., Prog. Theor. Phys. 63, 707-710 (1980)