Enhanced asymmetric valley scattering by scalar fields in non-uniform out-of-plane deformations in graphene

TL;DR

This paper investigates how scalar fields associated with charge redistribution in non-uniform out-of-plane deformations in graphene cause strong valley asymmetric scattering and polarization reversal, with potential applications in valleytronics.

Contribution

It introduces the role of scalar fields alongside pseudomagnetic fields in electron scattering in strained graphene, revealing new valley polarization behaviors.

Findings

Scalar fields induce strong valley asymmetric scattering.

Valley polarization can reverse sign with increasing energy.

Scalar fields enhance focusing and beam splitting effects.

Abstract

We study the electron scattering produced by local out-of-plane strain deformations in the form of Gaussian bumps in graphene. Of special interest is to take into account the scalar field associated with the redistribution of charge due to deformations, and in the same footing as the pseudomagnetic field. Working with the Born approximation approach we show analytically that even when a relatively small scalar field is considered, a rather strong valley asymmetric scattering could arise as a function of the energy and angle of incidence. In addition, we find that the valley polarization can reverse its sign as the incident energy is increased. These behaviors are totally absent if the scalar field is neglected. These results are supported by quantum dynamical simulations of electron wave packets. Results for the average trajectories of wave packets in locally strained graphene clearly show focusing and beam splitting effects enhanced by the presence of the scalar field that can be of interest in the implementation of valleytronic devices.