Avoided ferromagnetic quantum critical point: Antiferromagnetic ground state in substituted CeFePO

TL;DR

This study investigates substituted CeFePO compounds and finds that instead of a ferromagnetic quantum critical point, an antiferromagnetic ground state emerges, with notable metamagnetic transitions.

Contribution

It demonstrates that ferromagnetic quantum criticality is avoided in CeFePO by showing a transition to antiferromagnetism in substituted variants.

Findings

Antiferromagnetic ground state near quantum critical point

Pronounced metamagnetic transitions for H parallel to c

Ferromagnetic quantum critical point is avoided

Abstract

We have investigated single crystals of two substitution series Ce(Ru$_{1-x}$Fe$_{x}$)PO and CeFe(As$_{1-y}$P$_{y}$)O in the vicinity to the quantum critical material CeFePO by means of magnetic-susceptibility and specific-heat measurements. We observe an antiferromagnetic ground state in the vicinity of the quantum critical point, with pronounced metamagnetic transitions for $H\parallel c$, which is the magnetically hard direction. Our results verify that a ferromagnetic quantum critical point is avoided in substituted CeFePO, because we clearly demonstrate that the ferromagnetic ground state changes into an antiferromagnetic one, when approaching the quantum critical point.