Pressure and magnetic field dependence of the antiferromagnetism of PrFe4P12

Abstract

The compound PrFe4P12, which has the cubic LaFe4P12 modified CoAs3 -type structure, orders antiferromagnetically, with TN=6.2 K and with several field-induced magnetic transitions for T<TN, up to 5 T for T≪TN. Heat capacity measurements show the transition is a bulk effect, with magnetic entropy consistent with a magnetic doublet or triplet crystal-field ground state. dc magnetization measurements, M(H), at T=4.2 K up to 23 T reveal no further field-induced transitions, and M(H) attains only 54% of the Pr3+ free-ion moment at highest fields. Pulsed field measurements of dM/dH at 4.2 K up to 45 T fail to resolve further transitions. The transition to the antiferromagnetic state is accompanied by a very sharp Suezaki–Mori-type electrical resistivity transition due to critical scattering of electrons by spin fluctuations. Hydrostatic pressure decreases TN, (dTN/dP=−0.11 K/kbar), in sharp contrast to the behavior for the isomorphic semiconducting ferromagnet, UFe4P12 (TC=3.15 K; dTC/dP=+0.26 K/kbar). The field-induced magnetic transitions are also sharply reduced with pressure. The pressure dependence of the electrical resistivity showed a decrease in TN, with a concomitant decrease in the size of the Suezaki–Mori anomaly. The results are discussed in terms of crystal-field splittings of the Pr ion and possible hybridization effects.