Pressure-induced magnetic order of filled skutterudite compound PrFeP

Osakabe, Toyotaka  ; Kuwahara, Keitaro*; Kawana, Daichi; Iwasa, Kazuaki*

Filled skutterudite compound PrFeP shows the non-magnetic phase transition at T=6.5 K. Recent NMR measurements and theoretical works have predicted that the order parameter of the non-magnetic phase is the -type antiferro-quadropole. Under pressure above 2.5 GPa, the non-magnetic phase disappears and the new insulating phase appears, for example, below 9 K at 3.2 GPa. We have performed neutron diffraction experiments under pressure above 3 GPa using the triple-axis spectrometer TAS-1 installed at 2G beam port of JRR-3M in JAEA at Tokai in order to elucidate the order parameter of the pressure-induced insulating phase. We have successfully observed the distinct magnetic Bragg peak at (1,0,0) reciprocal lattice point at 3.2 GPa in the insulating phase. The peak corresponds to an antiferromagnetic long-range ordering of q = (1,0,0). The magnetic moments are 2.0 /Pr ions, which are align along the [0,0,1] direction. The results indicate that the insulating phase corresponds to the antiferromagnetically orderd phase and the order parameter is switched from the non-magnetic antiferro-quadropole to the antiderro-magnetic dipole by the pressurization of the lattice contraction of L/L0.5.