Kinetic properties and magnetic susceptibility of Pr0.67Ca0.33MnO3 under hydrostatic pressure

Abstract

Measurements of the magnetic susceptibility χ, thermopower α, and resistivity ρ of the manganate Pr1−xCaxMnO3 with x=0.33 are made on single-crystal samples in the temperature range 77–300 K and at pressures up to P=13 kbar. At P⩾8.8 kbar a metal-insulator transition is observed. The phase transition temperatures and their pressure dependence are obtained: the temperature of a possible structural transition Tn≈250 K (∂Tn/∂P=−1.7 K/kbar); the charge-ordering temperature Tco≈230 K (∂Tco/∂P=−0.8 K/kbar); the Néel temperature TN≈140 K (∂TN/∂P=−1.1 K/kbar); the temperature of the appearance of a spontaneous ferromagnetic moment TC≈100 K (∂TC/∂P=−1.2 K/kbar), and the temperature of the metal-insulator transition TMI (∂TMI/∂P=2.8 K/kbar). The α(T) curve is dome-shaped and is shifted into the negative region with increasing pressure, twice changing sign with the variation of the temperature. As TC is approached the thermopower α<0, with |α|>500 μV/K.