Quasiparticle interference of the Fermi arcs and surface-bulk connectivity of a Weyl semimetal

TL;DR

This study visualizes quasiparticle interference on the surface of a Weyl semimetal, revealing how Fermi arcs connect to bulk states and act as electron sinks, advancing understanding of topological surface-bulk interactions.

Contribution

It provides direct spectroscopic evidence of Fermi arc propagation into the bulk and their role as electron sinks, supported by a detailed theoretical model.

Findings

Identified 10 distinct scattering wave vectors.

Confirmed Fermi arc states propagate into the bulk.

Weyl nodes act as sinks for surface electron transport.

Abstract

Weyl semimetals host topologically protected surface states, with arced Fermi surface contours that are predicted to propagate through the bulk when their momentum matches that of the surface projections of the bulk's Weyl nodes. We use spectroscopic mapping with a scanning tunneling microscope to visualize quasi-particle scattering and interference at the surface of the Weyl semimetal TaAs. Our measurements reveal 10 different scattering wave vectors, which can be understood and precisely reproduced with a theory that takes into account the shape, spin texture, and momentum-dependent propagation of the Fermi arc surface states into the bulk. Our findings provide evidence that Weyl nodes act as sinks for electron transport on the surface of these materials.