Effect of Hydrostatic Pressure on the Electrical Resistivity of PrOs4Sb12up to 10 GPa

We have performed an electrical resistivity measurement of the heavy fermion superconductor PrOs 4 Sb 12 under hydrostatic pressures up to 10 GPa and at temperature down to ∼2 K. As pressure was increased to 8 GPa, a roll-off behavior in ρ( T ) around 5 K attributed to the CEF effect was slightly shifted to higher temperature region with remaining its shape almost the same. At 9 and 10 GPa, T 2 -dependences of resistivity were observed below ∼5 K without showing a roll-off in ρ( T ). The obtained A values in ρ= ρ 0 + A T 2 at 9 and 10 GPa were 0.32 and 0.20 µΩcm/K 2 , respectively. This fact suggests that the CEF state of PrOs 4 Sb 12 might be drastically changed at P > 8 GPa.