Ulloa Publishes ‘Minimal Geometry for Valley Filtering in Graphene’

Dr. Sergio Ulloa

Dr. Sergio E. Ulloa. Professor of Physics & Astronomy, coauthored “Minimal geometry for valley filtering in graphene.”

Authors: Asmar, MM; Ulloa, SE

Source: PHYSICAL REVIEW B, Volume 96, Issue 20; DOI: 10.1103/PhysRevB.96.201407

Published: November 2017

Abstract: The possibility to effect valley splitting of an electronic current in graphene represents the essential component in the new field of valleytronics in such two-dimensional materials. Based on a symmetry analysis of the scattering matrix, we show that if the spatial distribution of multiple potential scatterers breaks mirror symmetry about the axis of incoming electrons, then a splitting of the current between two valleys is observed. This leads to the appearance of the valley Hall effect. We illustrate the effect of mirror symmetry breaking in a minimal system of two symmetric impurities, demonstrating the splitting between valleys via the differential cross sections and non-vanishing skew parameter. We further discuss the role that these effects may play in transport experiments.