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

## TL;DR

This study demonstrates giant microwave-induced B-periodic magnetoresistance oscillations in a high-mobility 2DEG with a point contact, attributed to edge magnetoplasmon interference, with implications for sensitive microwave and terahertz spectrometers.

## Contribution

The paper provides experimental evidence of giant B-periodic oscillations caused by edge magnetoplasmons and clarifies the EMP interference length, aiding the design of advanced spectrometers.

## Key findings

- Giant oscillations with up to 700% amplitude observed.
- Interference length L exceeds the contact distance, matching edge contact separation.
- Analysis confirms EMP theory explains the oscillation periods.

## Abstract

We have studied the magnetoresistance of the quantum point contact fabricated on the high mobility two-dimensional electron gas (2DEG) exposed to microwave irradiation. The resistance reveals giant $B$-periodic oscillations with the relative amplitude $\Delta R/R$ of up to $700$\% resulting from the propagation and interference of the edge magnetoplasmons (EMPs) in the sample. This giant photoconductance is attributed to the considerably large local electron density modulation in the vicinity of the point contact. We have also analyzed the oscillation periods $\Delta B$ of the resistance oscillations and, comparing the data with the EMP theory, extracted the EMP interference length $L$. We have found that the length $L$ substantially exceeds the distance between the contact leads but rather corresponds to the distance between metallic contact pads measured along the edge of the 2DEG. This resolves existing controversy in the literature and should help to properly design highly sensitive microwave and terahertz spectrometers based on the discussed effect.