Characterization and manipulation of intervalley scattering induced by an individual monovacancy in graphene

TL;DR

This study visualized and controlled intervalley scattering caused by a single monovacancy in graphene, revealing its energy dependence and the effects of charging on scattering suppression, advancing understanding of defect-induced electronic properties.

Contribution

It provides direct imaging and manipulation of intervalley scattering from an individual atomic defect in graphene, a feat previously unachieved.

Findings

Intervalley scattering range is inversely proportional to energy.

Charging the monovacancy induces electron-hole asymmetry.

Charging softens the scattering potential, reducing scattering.

Abstract

Intervalley scattering involves microscopic processes that electrons are scattered by atomic-scale defects on nanometer length scales. Although central to our understanding of electronic properties of materials, direct characterization and manipulation of range and strength of the intervalley scattering induced by an individual atomic defect have so far been elusive. Using scanning tunneling microscope, we visualized and controlled intervalley scattering from an individual monovacancy in graphene. By directly imaging the affected range of intervalley scattering of the monovacancy, we demonstrated that it is inversely proportional to the energy, i.e., it is proportional to the wavelength of massless Dirac Fermions. A giant electron-hole asymmetry of the intervalley scattering is observed because that the monovacancy is charged. By further charging the monovacancy, the bended electronic potential around the monovacancy softened the scattering potential, which, consequently, suppressed the intervalley scattering of the monovacancy.