Interferometric measurement of Van Hove singularities in strained graphene

TL;DR

This paper introduces an interferometric technique to measure Van Hove singularities in strained graphene, revealing how their positions shift with stress magnitude and direction, providing insights into graphene's electronic properties.

Contribution

The study develops a novel interferometric method to detect Van Hove singularities in strained graphene and analyzes their dependence on stress magnitude and orientation.

Findings

Van Hove singularities appear as spectral dips or peaks.

Their positions shift with increasing tension strength.

Number and location depend on stress direction relative to the zigzag axis.

Abstract

This study presents a method based on the total internal reflection and the phase-shifting interferometry for measuring the Van Hove singularities in strained graphene. A linearly polarized light passes through some quarter- and half-wave plates, a hemi-cylindrical prism, and a Mach-Zehnder interferometer. The Van Hove singularities manifest themselves as some sharp dips or peaks in the spectrum of the final phase difference of the two interference signals. The numerical analysis demonstrates that the number of Van Hove singularities is independent of the modulus of the applied stress, but their position shifts as the strength of the tension increases. Besides, the number and location of singularities strongly depend on the stress direction relative to the zigzag axis in the graphene lattice. Moreover, we show that the location of singularities is independent of the tension direction relative to the tangential component of the electric field of the incident radiation.