Effects of doping and magnetic field on the half-metallic electronic structures ofLa1−xBaxMnO3

To deduce systematic trends in electronic and magnetic properties of colossal magnetoresistance (CMR) manganese oxides, we have investigated electronic structures of ${\mathrm{La}}_{1-x}{\mathrm{Ba}}_x{\mathrm{MnO}}_3$ with varying doping concentration. Assuming a virtual solid of LbMnO${}_3$, where Lb stands for a virtual atom with a fractional atomic number between La and Ba, we have studied effects of the doping and the magnetic field on the electronic structures of ${\mathrm{La}}_{1-x}{\mathrm{Ba}}_x{\mathrm{MnO}}_3$. It is found that the ${\mathrm{La}}_{1-x}{\mathrm{Ba}}_x{\mathrm{MnO}}_3$ system is half metallic in the doping range of $x>\mathrm{}0.33\mathrm{}$, and that it becomes half metallic even for $x<\mathrm{}0.33\mathrm{}$ by applying the magnetic field. The half-metallic property in the presence of the magnetic field is discussed in relation to the observed CMR effect in doped LaMnO${}_3$ systems.