Anomalous connection between antiferromagnetic and superconducting phases in pressurized non-centrosymmetric heavy fermion compound CeRhGe3

TL;DR

This study reveals an unusual relationship between antiferromagnetic and superconducting phases in pressurized CeRhGe3, where magnetic order abruptly vanishes near maximum superconductivity, linked to Ce valence instability.

Contribution

It uncovers a novel pressure-induced behavior where magnetic order avoids a continuous suppression, contrasting with typical superconducting transitions in heavy fermion compounds.

Findings

Antiferromagnetic transition abruptly terminates above 21.5 GPa.

Superconductivity reaches maximum near the magnetic transition point.

Ce valence instability correlates with magnetic and superconducting behavior.

Abstract

Unconventional superconductivity frequently emerges as the transition temperature of a magnetic phase, typically antiferromagnetic, is suppressed continuously toward zero temperature. Here, we report contrary behavior in pressurized CeRhGe3, a non-centrosymmetric heavy fermion compound. We find that its pressure-tuned antiferromagnetic transition temperature (TN) appears to avoid a continuous decrease to zero temperature by terminating abruptly above a dome of pressure-induced superconductivity. Near 21.5 GPa, evidence for TN suddenly vanishes, the electrical resistance becomes linear in temperature and the superconducting transition reaches a maximum. In light of X-ray absorption spectroscopy measurements, these characteristics appear to be related to a pressured-induced Ce valence instability, which reveals as a sharp increase in the rate of change of Ce valence with applied pressure.