Low-temperature properties of rare-earth and actinide iron phosphide compoundsMFe4P12(M= La, Pr, Nd, and Th)

The low-temperature properties of M${\mathrm{Fe}}_4$ ${\mathrm{P}}_{12}$ (M=La, Pr, Nd, and Th) single crystals have been studied by means of electrical-resistivity, magnetization, specific-heat, and magnetoresistivity measurements. Superconductivity among these compounds is known to occur only in ${\mathrm{LaFe}}_4$ ${\mathrm{P}}_{12}$, which has a superconducting transition temperature $T_c$ of ∼4 K. The compounds ${\mathrm{PrFe}}_4$ ${\mathrm{P}}_{12}$ and ${\mathrm{NdFe}}_4$ ${\mathrm{P}}_{12}$ display features that suggest the occurrence of antiferromagnetic ordering below ∼6.2 K and ferromagnetic ordering below ∼2 K, respectively. Isothermal magnetization curves for ${\mathrm{PrFe}}_4$ ${\mathrm{P}}_{12}$ below 6 K reveal a spin-flop or metamagnetic transition.