A highly asymmetric nodal semimetal in bulk SmB6

TL;DR

This paper reports the discovery of a highly asymmetric nodal semimetal in bulk SmB6, characterized by unusual low-temperature properties such as bulk de Haas-van Alphen oscillations and linear-in-temperature conductivity, suggesting a topological transformation.

Contribution

It introduces the concept of a highly asymmetric nodal semimetal in SmB6 arising from a topological transformation in a Kondo lattice with defects, challenging existing explanations involving a neutral Fermi surface.

Findings

Observation of bulk de Haas-van Alphen oscillations at millikelvin temperatures.

Detection of linear-in-temperature bulk electrical conductivity at liquid helium temperatures.

Proposed topological transformation as the origin of the semimetallic state.

Abstract

We show that novel low temperature properties of bulk SmB6, including the sudden growth of the de Haas-van Alphen amplitude (and heat capacity) originating from the bulk at millikelvin temperatures and a previously unreported linear-in-temperature bulk electrical conductivity at liquid helium temperatures, signal the presence of a highly asymmetric nodal semimetal. We show how the highly asymmetric nodal semimetal can be the result of a topological transformation, of the type recently considered by Shen and Fu, occurring in a Kondo lattice with dispersionless f-electron levels and Sm vacancies or other lattice defects. If supported by further data experimental, the existence of a nodal semimetal would cast considerable doubt over a neutral Fermi surface being required to explain the origin of the dHvA effect SmB6.