Transition from Metallic to Insulating Nature and Room Temperature Ferromagnetism of Fe0.05(SnTe) Bulk Alloy

We report metal to insulator transition of Fe0.05(SnTe) bulk alloy at transition temperature T-P, the value of which is found to decrease with increase in the applied field. This decrease could be attributed to the presence of lattice strain due to Fe doping into the SnTe system. The metallic region below T-P is described by a model based on electron-electron, electron-phonon and electron-magnon scattering, and further upturn in resistivity at low temperatures is explained on the lines of Kondo-like scattering. The high temperature insulating region is suitably explained using small polaron hopping model. Zero-field cooled (ZFC) and field-cooled (FC) measurements are carried out under an applied magnetic field of 200 Oe, and the blocking temperature (T-B) is found to be above room temperature. Below room temperature, the sample shows ferromagnetic behaviour having very small value of coercivity (H-C) which is also confirmed by the presence of spontaneous magnetization in the Arrott plot. The magnitude of magnetoresistance measurement is found to be positive at low temperatures and is explained on the basis of shrinkage of wave function.