Optical absorption and transverse Kerr effect spectra, resistivity, and magnetoresistance of La 1Ϫx Sr x CoO 3 (xϭ0.15,0.25,0.35) films have been studied. The temperature dependences of the optical and magneto-optical properties of the films exhibit features which can be attributed to the transition of the Co 3ϩ ions from the low-spin state (Sϭ0) to the intermediate-spin state (Sϭ1) and to orbital ordering of the Co 3ϩ ions in the latter state. The evolution of the properties influenced by doping with Sr is interpreted on the basis of the phase separation model.

Resistivity, thermoelectric power, heat capacity, and magnetization for samples of RuSr2(Gd1.5Ce0.5)Cu2O10−δ were investigated in the temperature range 1.8–300K with a magnetic field up to 8T. The resistive transitions to the superconducting state are found to be determined by the inhomogeneous (granular) structure, characterized by the intragranular, Tc0, and intergranular, Tcg, transition temperatures. Heat capacity, C(T), shows a jump at the superconducting transition temperature Tc0≈37.5K. A Schottky-type anomaly is found in C(T) below 20K. This low-temperature anomaly can be attributed to splitting of the ground term S7∕28 of paramagnetic Gd3+ ions by internal and external magnetic fields.

No abstract

No abstract