Intergranular magnetoresistance of strontium ferromolybdate ceramics caused by spin-polarized tunneling

In this work, we develop a model for the description of the low-field magnetoresistance of Sr₂FeMoO_6−δ ceramics that, for the very first time, is considering the magnetic field dependence of the tunneling barrier height. The core of the model is the temperature and magnetic field dependence of the reduced magnetization m. Spin polarization is considered as a function of temperature and antisite disordering. A magnetic field dependence of the intergrain barrier height was supposed. The model satisfactorily describes the low field magnetoresistance for magnetic fields exceeding several times the coercive field.