Half-metallic electronic structures of colossal magnetoresistance manganese oxides

Abstract

Using the virtual crystal approximation, we have studied electronic and magnetic properties of the colossal magnetoresistance (CMR) La1-xBaxMnO3 system at general doping concentrations. We have studied the change of the electronic structure and the Fermi surface topology as a function of the doping a: for 0.2 < x < 0.5, where the system is a ferromagnetic metal with cubic structure. La1-xBaxMnO3 system undergoes a phase transition from a normal metallic ferromagnet to a half-metal at x = 0.33 where the CMR is observed. We have also studied the effect of the magnetic field and found that the magnetic field induces a half-metallic transition, and so enhances the magnetoresistance.