Unidirectional Kondo scattering in layered NbS2

TL;DR

This paper reports an unexpected unidirectional Kondo scattering in layered NbS2 crystals, revealing highly anisotropic magnetic interactions influenced by crystalline defects and charge-density-wave reconstructions.

Contribution

It uncovers a novel unidirectional Kondo effect in NbS2, showing how defects induce anisotropic magnetic scattering in layered conductors.

Findings

Unidirectional Kondo scattering observed below 40 K

Anisotropic response to magnetic fields along different axes

Kondo lattice heterostructure formed by defects

Abstract

Crystalline defects can modify quantum interactions in solids, causing unintuitive, even favourable, properties such as quantum Hall effect or superconducting vortex pinning. Here we present another example of this notion - an unexpected unidirectional Kondo scattering in single crystals of 2H-NbS2. This manifests as a pronounced low-temperature enhancement in the out-of-plane resistivity and thermopower below 40 K, hidden for the in-plane charge transport. The anomaly can be suppressed by the c-axis-oriented magnetic field, but is unaffected by field applied along the planes. The magnetic moments originate from layers of 1T-NbS2, which inevitably form during the growth, undergoing a charge-density-wave reconstruction with each superlattice cell (David-star-shaped cluster of Nb atoms) hosting a localised spin. Our results demonstrate the unique and highly anisotropic response of a spontaneously formed Kondo lattice heterostructure, intercalated in a layered conductor.