Emergent Topological Semimetal

TL;DR

This paper reports the discovery of an emergent topological semimetal phase arising from a quantum critical heavy fermion compound, revealing topological features beyond the quasiparticle framework.

Contribution

It introduces a topological semimetal phase emerging from quantum criticality in heavy fermion systems, supported by experimental and theoretical analysis of a Weyl-Kondo model.

Findings

Discovery of a topological semimetal phase in CeRu$_4$Sn$_6$ at quantum criticality.

Spectral features indicating topological crossings beyond quasiparticles.

Model calculations showing topological features at a Kondo destruction quantum critical point.

Abstract

A material's electronic topology, which is generally described via its Bloch states and the associated bandstructure, will be enriched by the presence of interactions. In metallic settings, the interactions are usually treated through the concept of quasiparticles. Using the genuinely quantum critical heavy fermion compound CeRu$_4$Sn$_6$, we investigate what happens if no well-defined quasiparticles are present. Surprisingly, we discover a topological semimetal phase that emerges from the material's quantum critical state and exhibits a dome structure as a function of magnetic field and pressure. To understand these results, we study a Weyl-Kondo semimetal model at a Kondo destruction quantum critical point. Indeed, it exhibits features in the spectral function that can define topological crossings beyond the quasiparticle picture. We expect our work to stimulate the search for other emergent topological phases.