Quantum phase transition and destruction of Kondo effect in pressurized SmB6

TL;DR

This study investigates how applying pressure to SmB6 affects its electronic gaps and reveals a quantum phase transition from a topological Kondo insulator to a Fermi-liquid state around 4 GPa, highlighting the interplay of correlations and topology.

Contribution

It provides experimental evidence of a pressure-induced quantum phase transition in SmB6, linking gap evolution, Kondo destruction, and topological state changes.

Findings

Identification of a pressure-induced quantum phase transition at ~4 GPa

Observation of Kondo hybridization gap collapse under pressure

Evidence of Kondo entanglement destruction in a mixed-valence state

Abstract

SmB6 is a promising candidate material that promises to elucidate the connection between strong correlations and topological electronic states, which is a major challenge in condensed matter physics. The electron correlations are responsible for the development of multiple gaps in SmB6, whose elucidation is sorely needed. Here we do so by studying the evolutions of the gaps and other corresponding behaviors under pressure. Our measurements of the valence, Hall effect and electrical resistivity clearly identify the gap which is associated with the bulk Kondo hybridization and, moreover, uncover a pressure-induced quantum phase transition from the putative topological Kondo insulating state to a Fermi-liquid state at ~4 GPa. We provide the evidences for the transition by a jump of inverse Hall coefficient, a diverging tendency of the electron-electron scattering coefficient and, thereby, a destruction of the Kondo entanglement in the ground state. These effects take place in a mixed-valence background. Our results raise the new prospect for studying topological electronic states in quantum critical materials settings.