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Curveball electrons: Valley transport in gapped Dirac materials

Speaker: 
Justin Song (Caltech, USA)
Date: 
Wed, 26/08/2015 - 11:00am to 12:00pm
Location: 
New Physics Conference Room (S11-02-07)
Event Type: 
Seminars

Abstract

Charge carriers in materials are often described as quasiparticles similar to free electrons and can be characterized by effective quantities such as an effective mass. However, electrons in topological materials acquire an additional quantum mechanical property - Berry curvature - that is the key ingredient in a range of new phenomena. A striking example is carrier dynamics in gapped Dirac systems, such as graphene on hexagonal-boron-nitride (G/h-BN). I will discuss how Berry curvature gives rise to transverse valley currents even in the absence of a magnetic field in these systems. Crucially, these valley currents do not depend on the presence of edge states, and persist even in the gapped system bulk. These anomalous carrier dynamics manifest naturally in G/h-BN, displaying large non-local resistances mediated by valley currents in G/h-BN devices, yielding a new platform/scheme to access topological characteristics in layered 2D stacks of materials.

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