Fermi arc induced vortex structure in Weyl beam shifts

TL;DR

This paper demonstrates that beam reflections in Weyl media exhibit vortex-like shifts influenced by Fermi arc surface states, linking bulk geometrical effects with topological surface phenomena for probing Weyl topologies.

Contribution

It reveals how beam shifts in Weyl materials are affected by Fermi arcs, establishing a connection between bulk geometrical effects and surface topological states.

Findings

Beam shifts form a half-vortex in surface momentum space.

Shift magnitude diverges at the Fermi arc touching point.

Bulk transport can probe Weyl topological characteristics.

Abstract

In periodic media, despite the close relationship between geometrical effects in the bulk and topological surface states, the two are typically probed separately. We show that when beams in a Weyl medium reflect off an interface with a gapped medium, the trajectory is influenced by both bulk geometrical effects and the Fermi arc surface states. The reflected beam experiences a displacement, analogous to the Goos-H\"anchen or Imbert-Fedorov shifts, that forms a half-vortex in the two-dimensional surface momentum space. The half-vortex is centered where the Fermi arc of the reflecting surface touches the Weyl cone, with the magnitude of the shift scaling as an inverse square root away from the touching-point, and diverging at the touching-point. This striking feature provides a way to use bulk transport to probe the topological characteristics of a Weyl medium.