标题： 四极相变在4$f^2$ fcc晶格化合物PrCdNi$_{4}$中 显示英文标题

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

摘要： 运输和磁性性质的4$f^{2}$ fcc晶格化合物，PrCdNi$_4$，被研究。磁化率，$\chi(T)$，从300 K到20 K遵循居里-维斯定律，这符合自由Pr$^{3+}$离子的预期。当温度降低到5 K以下时，$\chi(T)$趋近于一个常数，表明具有范弗勒克顺磁行为。 比热，$C(T)$，在约4 K处显示一个宽的肩峰，这可以通过一个具有12 K能隙的双重态三重态两能级模型来再现。这些结果表明，在立方晶体电场中Pr$^{3+}$离子具有非磁性的$\Gamma_3$双重态基态。$C(T)$在$T_{\rm O}$= 1.0 K处出现峰值，并且该峰值在高达5 T的磁场下仍然保持稳定。在粉末中子衍射测量中，在0.32 K$<$$T_{\rm O}$未观察到磁性反射。 在磁阻中，$B$ = 2.1 和 5.3 T 处的两个异常现象，在 0.05 K 时的 $\rho(B)$可能来源于序参量的切换。这些结果表明，$T_{\rm O}$处的相变归因于 4$f^2$面心立方晶格中 $\Gamma_3$双重态的电四极矩或磁八极矩的反铁型序。 显示英文摘要

摘要： 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 $T_{\rm O}$ = 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 $<$ $T_{\rm O}$. 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 $T_{\rm O}$ 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.