Multipolar Phase Transition in the 4$f^2$ fcc lattice compound PrCdNi${}_4$

Abstract

Transport and magnetic properties of a 4$f^2$ fcc lattice compound, PrCdNi${}_4$, were studied. The magnetic susceptibility, $\chi (T)$, follows the Curie--Weiss law from 300 K to 20 K, as expected for a free Pr${}^{3+}$ ion. As the temperature decreases below 5 K, $\chi (T)$ approaches a constant, indicating van-Vleck paramagnetic behavior. The specific heat, $C(T)$, displays a broad shoulder at around 4 K, which can be reproduced by a doublet triplet two-level model with an energy gap of 12 K. These results suggest a non-magnetic ${\Gamma }_3$ doublet ground state of the Pr${}^{3+}$ ion in the cubic crystalline electric field. $C(T)$ exhibits a peak at $T_{\mathrm{O}}$ = 1.0 K and this peak remains robust against magnetic fields up to 5 T. In powder neutron diffraction measurements, no magnetic reflection was observed at 0.32 K $<$ $T_{\mathrm{O}}$. Two anomalies at $B$ = 2.1 and 5.3 T in magnetoresistance $\rho (B)$ at 0.05 K likely originate from switching in the order parameter. These results suggest that the phase transition at $T_{\mathrm{O}}$ is ascribed to an antiferro-type order of the electric quadrupole or magnetic octupole of the ${\Gamma }_3$ doublet in the 4$f^2$ fcc lattice.

10 pages, 8 figures. Additional 5 pages, 4 figures 3 tables in supplemental material