Magnetic, transport, and electron magnetic resonance properties of Pr0.8Ca0.2MnO3 single crystals -: art. no. 094428

Magnetic, transport, and electron magnetic resonance properties of Pr0.8Ca0.2MnO3 single crystals have been investigated. Two ferromagnetic transitions observed at T(C1)approximate to130 K and T(C2)approximate to60 K, denote a long range ordering of Mn and Pr spins, respectively, and exhibit an opposite pressure coefficient for T-C, dT(C1)/dPapproximate to0.24 K/kbar and dT(C2)/dPapproximate to-0.75 K/kbar, respectively. The angular dependence of the magnetization in the (100) plane shows a strong twofold anisotropy, which increases under pressure. It was found that the resistivity rho(T) obeys the Arrhenius law at 140 Kless than or equal toTless than or equal to300 K with an activation energy E-a=130 meV, whereas below T-C1, E-a=60 meV. The dynamic magnetoresistance vs magnetic field approaches a highest value of about 25% near T-C1 for H=14.5 kOe. The dynamic resistance R-d exhibits a pronounced dependence on a bias current I at T