Direct observation of the quantum critical point in heavy fermion CeRhSi$_3$

TL;DR

This study uses muon spin rotation to directly observe the quantum critical point in CeRhSi$_3$, revealing how magnetic order is suppressed under pressure leading to a quantum phase transition within the superconducting phase.

Contribution

First direct observation of the quantum critical point in CeRhSi$_3$ through pressure-dependent muon spin rotation measurements.

Findings

Magnetic moments are gradually quenched with pressure.

Ordered magnetic moments are fully suppressed at 23.6 kbar.

Quantum critical point occurs inside the superconducting phase.

Abstract

We report on muon spin rotation studies of the noncentrosymmetric heavy fermion antiferromagnet CeRhSi$_3$. A drastic and monotonic suppression of the internal fields, at the lowest measured temperature, was observed upon an increase of external pressure. Our data suggest that the ordered moments are gradually quenched with increasing pressure, in a manner different from the pressure dependence of the N\'eel temperature. At $\unit{23.6}{kbar}$, the ordered magnetic moments are fully suppressed via a second-order phase transition, and $T_{\rm{N}}$ is zero. Thus, we directly observed the quantum critical point at $\unit{23.6}{kbar}$ hidden inside the superconducting phase of CeRhSi$_3$.