Possible Weyl fermions in the magnetic Kondo system CeSb

TL;DR

This paper presents evidence for Weyl fermions in the ferromagnetic state of the Kondo system CeSb, combining electronic structure calculations and magnetoresistance measurements, revealing a new class of topological Kondo materials.

Contribution

It demonstrates the existence of Weyl fermions in a strongly correlated Kondo lattice, a novel finding linking topological physics with Kondo systems.

Findings

Negative magnetoresistance observed in ferromagnetic state

Weyl fermions identified via electronic structure calculations

Field orientation affects magnetoresistance behavior

Abstract

Materials where the electronic bands have unusual topologies allow for the realization of novel physics and have a wide range of potential applications. When two electronic bands with linear dispersions intersect at a point, the excitations could be described as Weyl fermions which are massless particles with a particular chirality. Here we report evidence for the presence of Weyl fermions in the ferromagnetic state of the low-carrier density, strongly correlated Kondo lattice system CeSb, from electronic structure calculations and angle-dependent magnetoresistance measurements. When the applied magnetic field is parallel to the electric current, a pronounced negative magnetoresistance is observed within the ferromagnetic state, which is destroyed upon slightly rotating the field away. These results give evidence for CeSb belonging to a new class of Kondo lattice materials with Weyl fermions in the ferromagnetic state.