Pseudospin rotation and valley mixing in electron scattering at graphene edges

TL;DR

This paper explores how pseudospin and valley degrees of freedom influence electron scattering at graphene edges, revealing their correlation with charge density patterns and implications for valleytronics and pseudospintronics applications.

Contribution

It provides a combined theoretical and experimental analysis of pseudospin and valley effects in graphene edge scattering, advancing understanding for valleytronics and pseudospintronics.

Findings

Charge density modulations linked to pseudospin and valley effects

Agreement between theoretical models and STM experimental data

Potential applications in valleytronics and pseudospintronics

Abstract

In graphene, the pseudospin and the valley flavor arise as new types of quantum degrees of freedom due to the honeycomb lattice comprising two sublattices (A and B) and two inequivalent Dirac points (K and K') in the Brillouin zone, respectively. Unique electronic properties of graphene result in striking phenomena such as Klein tunnelling, Veselago lens, and valley-polarized currents. Here, we investigate the roles of the pseudospin and the valley in electron scattering at graphene edges and show that they are strongly correlated with charge density modulations of short-wavelength oscillations and slowly-decaying beat patterns. Theoretical analyses using nearest-neighbor tight-binding methods and first-principles density-functional theory calculations agree well with our experimental data from the scanning tunneling microscopy. We believe that this study will lead to useful application of graphene to "valleytronics" and "pseudospintronics".