Tunable Weyl and Dirac states in the nonsymmorphic compound $\rm\mathbf{CeSbTe}$

TL;DR

This paper demonstrates that the compound CeSbTe can host a variety of topological semimetal states, including exotic phases with manifold band degeneracies, which can be tuned via magnetic order, making it a versatile platform for studying magnetism-topology interplay.

Contribution

It reveals CeSbTe as the first nonsymmorphic magnetic topological material with tunable topological phases driven by magnetic order.

Findings

Realization of multiple topological semimetal states in CeSbTe

Observation of an eight-fold band crossing at a high symmetry point

Magnetic order tuning drives transitions between topological phases

Abstract

Recent interest in topological semimetals has lead to the proposal of many new topological phases that can be realized in real materials. Next to Dirac and Weyl systems, these include more exotic phases based on manifold band degeneracies in the bulk electronic structure. The exotic states in topological semimetals are usually protected by some sort of crystal symmetry and the introduction of magnetic order can influence these states by breaking time reversal symmetry. Here we show that we can realize a rich variety of different topological semimetal states in a single material, $\rm CeSbTe$. This compound can exhibit different types of magnetic order that can be accessed easily by applying a small field. It allows, therefore, for tuning the electronic structure and can drive it through a manifold of topologically distinct phases, such as the first nonsymmorphic magnetic topological material with an eight-fold band crossing at a high symmetry point. Our experimental results are backed by a full magnetic group theory analysis and ab initio calculations. This discovery introduces a realistic and promising platform for studying the interplay of magnetism and topology.