Transport and magnetic properties of pressure-induced insulating phase in PrFe₄P₁₂

We have studied the physical properties of a pressure-induced insulating phase in PrFe₄P₁₂ via Hall effect, ³¹P-NMR and magnetization measurements under quasi-hydrostatic pressure. In the Hall effect measurement, a decrease in the number of hole carriers due to the metal-insulator (M-I) transition is confirmed, indicating a band insulating state. The ³¹P-NMR spectrum exhibits abrupt broadening and the susceptibility is suppressed markedly owing to the M-I transition, suggesting that an antiferromagnetic ordering occurs in the insulating phase and the M-I transition is of first order. Both spectra corresponding to the metallic and insulating phases are observed simultaneously in a wide temperature range near the M-I transition. This fact reflects the sensitivity of the M-I transition to uniaxial stress, which is confirmed in the resistivity measurement under uniaxial stress.