Topological Lifshitz Transitions and Fermi Arc Manipulation in Weyl Semimetal NbAs

TL;DR

This paper demonstrates manipulation of surface Fermi arcs in the Weyl semimetal NbAs, revealing a topological Lifshitz transition driven by surface modifications rather than carrier concentration changes.

Contribution

It introduces a method to control Fermi arc configurations in NbAs and uncovers a novel Lifshitz transition linked to surface topology changes.

Findings

Successful manipulation of Fermi arc shape and connections

Observation of a Lifshitz transition without carrier doping

Fermi arcs remain topologically protected despite surface evolution

Abstract

Surface Fermi arcs (SFAs), the unique open Fermi-surfaces (FSs) discovered recently in topological Weyl semimetals (TWSs), are unlike closed FSs in conventional materials and can give rise to many exotic phenomena, such as anomalous SFA-mediated quantum oscillations, chiral magnetic effects, three-dimensional quantum Hall effect, non-local voltage generation and anomalous electromagnetic wave transmission. Here, by using in-situ surface decoration, we demonstrate successful manipulation of the shape, size and even the connections of SFAs in a model TWS, NbAs, and observe their evolution that leads to an unusual topological Lifshitz transition not caused by the change of the carrier concentration. The phase transition teleports the SFAs between different parts of the surface Brillouin zone. Despite the dramatic surface evolution, the existence of SFAs is robust and each SFA remains tied to a pair of Weyl points of opposite chirality, as dictated by the bulk topology.