Detecting Strain Effects due to Nanobubbles in Graphene Mach-Zehnder Interferometers

TL;DR

This paper studies how nanobubbles induce strain in graphene Mach-Zehnder interferometers, affecting conductance oscillations and demonstrating potential for graphene-based strain sensing.

Contribution

It reveals how nanobubbles cause detuning of quantum Hall oscillations via pseudo-magnetic fields and introduces machine learning Fourier analysis to differentiate these effects.

Findings

Nanobubbles cause conductance oscillation detuning due to strain-induced pseudo-magnetic fields.

A new Fourier component at $\

Phi_{0}/2\

Abstract

We investigate the effect of elastic strain on a Mach-Zehnder (MZ) interferometer created by graphene p-n junction in quantum Hall regime. We demonstrate that a Gaussian-shaped nanobubble causes detuning of the quantum Hall conductance oscillations across the p-n junction, due to the strain-induced local pseudo-magnetic fields. By performing a machine-learning-based Fourier analysis, we differentiate the nanobubble-induced Fourier component from the conductance oscillations originating from the external magnetic fields. We show that the detuning of the conductance oscillations is due to the altered pathway of quantum Hall interface channels caused by the strain-induced pseudo-magnetic fields. In the presence of the nanobubble, a new Fourier component for a magnetic flux $\Phi_{0}/2$ appears, and the corresponding MZ interferometry indicates that the enclosed area is reduced by half due to the strain-mediated pathway between two quantum Hall interface channels. Our findings suggest the potential of using graphene as a strain sensor for developments in graphene-based device fabrications and measurements technologies.