论文部分内容阅读
The electrical transport and magnetic properties of the colossal magnetoresistance material FeCr2S4 are studied.The temperature dependence of resistivity p and thermoelectric power S are investigated from 5 to 300K andfrom 77 to 300K, respectively. The activation energy Eρ obtained from p - T is larger than the activationenergy Es, obtained from S - T. This indicates that magnetic polarons dominate the conduction behaviour attemperatures above Tc. The M- T curve and electron spin resonance spectra show that the paramagneticferromagnetic transition is incomplete, and that a paramagnetic phase coexists with a ferromagnetic phase in a certain temperature range below Tc. It is proposed that the insulator-metal transition near Tc could beattributed to the gradual delocalizing effect from magnetic polarons to naked carriers. The resistivity in thepresented temperature range can be described by considering the coexistence of magnetic polarons and naked carriers.