Giant microwave-induced $B$-periodic magnetoresistance oscillations in a two-dimensional electron gas with a bridged-gate tunnel point contact

摘要

We have studied the magnetoresistance of the quantum point contact fabricatedon the high mobility two-dimensional electron gas (2DEG) exposed to microwaveirradiation. The resistance reveals giant $B$-periodic oscillations with therelative amplitude $\Delta R/R$ of up to $700$\% resulting from the propagationand interference of the edge magnetoplasmons (EMPs) in the sample. This giantphotoconductance is attributed to the considerably large local electron densitymodulation in the vicinity of the point contact. We have also analyzed theoscillation periods $\Delta B$ of the resistance oscillations and, comparingthe data with the EMP theory, extracted the EMP interference length $L$. Wehave found that the length $L$ substantially exceeds the distance between thecontact leads but rather corresponds to the distance between metallic contactpads measured along the edge of the 2DEG. This resolves existing controversy inthe literature and should help to properly design highly sensitive microwaveand terahertz spectrometers based on the discussed effect.