Electrical control of intervalley scattering in graphene via the charge state of defects

TL;DR

This study demonstrates that the charge state of defects in graphene can be electrically controlled to suppress intervalley scattering, offering a new way to manipulate valley relaxation in valleytronic materials.

Contribution

It reveals how defect charge states influence intervalley scattering in graphene and shows that electrical tuning can control valley dynamics, with potential applications in valleytronics.

Findings

Charged defects suppress intervalley scattering.

Long-range Coulomb potential screens short-range scattering.

Electrical tuning of defect charge states controls valley relaxation.

Abstract

We study the intervalley scattering in defected graphene by low-temperature transport measurements. The scattering rate is strongly suppressed when defects are charged. This finding highlights "screening" of the short-range part of a potential by the long-range part. Experiments on calcium-adsorbed graphene confirm the role of a long-range Coulomb potential. This effect is applicable to other multivalley systems, provided that the charge state of a defect can be electrically tuned. Our result provides a means to electrically control valley relaxation and has important implications in valley dynamics in valleytronic materials.