Transport and torque magnetometry measurements on CeAuSb$_{2}$

The tetragonal crystal CeAuSb$_{2}$ has a layered structure and orders antiferromagnetically at T $\sim$ 6K. Under a c-axis magnetic field, the Neel temperature is gradually suppressed to zero at a possible field-tuned quantum critical point at about 6 T. Within this antiferromagnetic phase, between the QCP and about 2.8 T, there is an additional, novel phase. We report transport measurements on pure single crystals of CeAuSb$_{2}$, in fields of up to 35 T and from room temperature down to 100 mK. We also report torque magnetometry measurements. Unlike a recent report, we find single, sharp transitions into the novel phase. We discuss the nature of the novel phase.\\[4pt] The work presented is supported by TOPNES(Topological Protection and Non-Equilibrium States in Strongly Correlated Electron Systems research programme), the Engineering and Physical Sciences Research Council (EPSRC, UK) and Max Planck Institute for Chemical Physics of Solids(Dresden, Germany) etc.