Large intravalley scattering due to pseudo-magnetic fields in crumpled graphene

TL;DR

This study demonstrates that pseudo-magnetic fields in crumpled graphene cause significant intravalley scattering, evidenced by Raman spectra and numerical calculations, revealing new insights into electron behavior under strain-induced pseudo-magnetic fields.

Contribution

It provides experimental and theoretical evidence that pseudo-magnetic fields in crumpled graphene induce intravalley scattering, lifting previous restrictions on backscattering of Dirac fermions.

Findings

Increased D'/D peak ratio in Raman spectra of crumpled graphene

Numerical calculations confirm phase shift in Dirac carriers due to pseudo-magnetic fields

Pseudo-magnetic fields enable intravalley backscattering of Dirac fermions

Abstract

The pseudo-magnetic field generated by mechanical strain in graphene can have dramatic consequences on the behavior of electrons and holes. Here we show that pseudo-magnetic field fluctuations present in crumpled graphene can induce significant intravalley scattering of charge carriers. We detect this by measuring the confocal Raman spectra of crumpled areas, where we observe an increase of the D'/D peak intensity ratio by up to a factor of 300. We reproduce our observations by numerical calculation of the double resonant Raman spectra and interpret the results as experimental evidence of the phase shift suffered by Dirac charge carriers in the presence of a pseudo-magnetic field. This lifts the restriction on complete intravalley backscattering of Dirac fermions.