Electronic topological transition in sliding bilayer graphene

TL;DR

This paper theoretically demonstrates that tiny lateral shifts in bilayer graphene cause a sensitive topological transition in energy bands and Fermi surface, driven by non-Abelian gauge fields affecting measurable electronic properties.

Contribution

It reveals how minute interlayer shifts induce topological transitions via non-Abelian gauge fields, a novel insight into bilayer graphene's electronic behavior.

Findings

Topological transition occurs with tiny lateral shifts

Generation of effective non-Abelian vector potential in Dirac Hamiltonian

Observable effects include anomalous density of states and Landau levels

Abstract

We demonstrate theoretically that the topology of energy bands and Fermi surface in bilayer graphene undergoes a very sensitive transition when extremely tiny lateral interlayer shift occurs in arbitrary directions. The phenomenon originates from a generation of effective non-Abelian vector potential in Dirac Hamiltonian by the sliding motions. The characteristics of the transition such as pair annihilations of massless Dirac fermions are dictated by the sliding direction owing to a unique interplay between the effective non-Abelian gauge fields and Berry's phases associated with massless electrons. The transition manifests itself in various measurable quantities such as anomalous density of states, minimal conductivity, and distinct Landau level spectrum.