Nematic State in CeAuSb_{2}

Abstract

At ambient pressure and zero field, tetragonal CeAuSb_{2} hosts stripe antiferromagnetic order at T_{N}=6.3 K. Here, we first show via bulk thermodynamic probes and x-ray diffraction measurements that this magnetic order is connected with a structural phase transition to a superstructure that likely breaks C_{4} symmetry, thus signaling nematic order. The temperature-field-pressure phase diagram of CeAuSb_{2} subsequently reveals the emergence of additional ordered states under applied pressure at a multicritical point. Our phenomenological model supports the presence of a vestigial nematic phase in CeAuSb_{2} akin to iron-based high-temperature superconductors; however, superconductivity, if present, remains to be discovered.