Temperature–field phase diagram of quantum critical CeAuSb 2

CeAuSb 2 has previously been classified as an antiferromagnet with moderately enhanced electron masses. As the magnetic order is suppressed by a magnetic field, non‐Fermi liquid behaviour has been shown to emerge, suggesting the presence of a quantum critical point (QCP). Within the ordered phase a metamagnetic transition was detected. Here we investigate the material by isothermal magnetization M ( H ), transverse magnetoresistivity ρ t ( H ) and Hall resistivity ρ H ( H ) measurements. We show that the metamagnetic transition splits into two first order transitions below 2 K. Pronounced anomalies in ρ t ( H ) and ρ H ( H ) are not only observed at the QCP and the metamagnetic transitions but also at a new characteristic field above the QCP.