Influence of Microwave Excitation‐Power on the Narrow Negative Magnetoresistance Effect Around B = 0 T in the Ultra‐High Mobility GaAs/AlGaAs 2DES

Abstract

In addition to the photo‐excited zero‐resistance states and radiation‐induced magnetoresistance oscillations, which can be observed in the high‐quality GaAs/AlGaAs two‐dimensional electron system (2DES), magnetotransport studies of this 2DES also exhibit interesting dark magnetoresistance effects. Here, a narrow negative magnetoresistance (MR) effect that appears around zero field, and spans over about −0.02 T ≤ B ≤ 0.02 T is examined. This experimental work aims to study the influence of microwave (MW) photo‐excitation on this narrow negative‐MR effect in high‐mobility GaAs/AlGaAs 2DES. Experimental data exhibit that the observed negative magnetoresistance effect disappears with increasing MW power. For example, the change in magnetoresistance (ΔRxx) due to the narrow negative‐MR effect drops by ≈50% upon increasing the source power up to about 8 mW. Further analysis shows that the zero‐field resistance monotonically increases with increasing the power, suggesting that electron heating due to the energy absorbed from the radiation field accounts for the observed quenching of the narrow negative‐MR effect.