Equilibration of quantum hall edge states and its conductance fluctuations in graphene p-n junctions

TL;DR

This paper investigates conductance fluctuations in graphene p-n junctions under quantum Hall conditions, showing how these fluctuations diminish with temperature and bias, aligning with theoretical models of edge state equilibration.

Contribution

It provides experimental evidence of conductance fluctuation behavior in graphene quantum Hall p-n junctions and compares results with random matrix theory predictions.

Findings

CFs decrease with increasing bias and temperature

CFs vanish above 7 K, restoring quantized plateaus

Experimental CFs trend aligns with theoretical predictions at high filling factors

Abstract

We report an observation of conductance fuctuations (CFs) in the bipolar regime of quantum hall (QH) plateaus in graphene (p-n-p/n-p-n) devices. The CFs in the bipolar regime are shown to decrease with increasing bias and temperature. At high temperature (above 7 K) the CFs vanishes completely and the flat quantized plateaus are recovered in the bipolar regime. The values of QH plateaus are in theoretical agreement based on full equilibration of chiral channels at the p-n junction. The amplitude of CFs for different filling factors follows a trend predicted by the random matrix theory. Although, there are mismatch in the values of CFs between the experiment and theory but at higher filling factors the experimental values become closer to the theoretical prediction. The suppression of CFs and its dependence has been understood in terms of time dependent disorders present at the p-n junctions.