Anomaly of Specific Heat in High Quality Single Crystal of PrAg2In

Abstract

PrAg2In has a non-Kramers doublet Λ3 ground state, which is expected to show a quadrupolar phenomena. Although many studies have been devoted to investigate the novel features of PrAg2In, there is no clear result how to remove the degeneracy of quadrupolar moment because this compound has a Heusler structure, in which the substitution between Pr and In ions is inevitable. We therefore prepare a high quality single crystal of PrAg2In with the residual resistivity ratio of 14, which is much larger than that of the previous samples. We measure the magnetic susceptibility with the SQUID magnetometer down to T = 0.4 K and the specific heat in the magnetic fields up to H = 8T along [100] crystal direction down to T =0.1 K. The susceptibility is consistent with the CEF calculation. The specific heat shows a sharp peak at around Tp = 0.33 K. When the magnetic field is applied, the peak at TP does not move up to H = 2.5 T. In contrast, it shifts to higher temperatures with broadening above H = 2.5 T. The broad peak above H = 2.5 T is well reproduced by the Schottky specific heat due to the splitting of the Λ3 doublet in the magnetic fields. From these results, we conclude that a phase transition related to the r3 doublet occurs at around TP.