EFFECTS OF DOPING AND MAGNETIC-FIELD ON THE HALF-METALLIC ELECTRONIC-STRUCTURES OF LA1-XBAXMNO3

To deduce systematic trends in electronic and magnetic properties of c olossal magnetoresistance (CMR) manganese oxides, we have investigated electronic structures of La1-xBaxMnO3 with varying doping concentrati on. Assuming a virtual solid of LbMnO(3), where Lb stands for a virtua l atom with a fractional atomic number between La and Ba, we have stud ied effects of the doping and the magnetic field on the electronic str uctures of La1-xBaxMnO3. It is found that the La1-xBaxMnO3 system is h alf metallic in the doping range of x>0.33, and that it becomes half m etallic even for x<0.33 by applying the magnetic held. The half-metall ic property in the presence of the magnetic field is discussed in rela tion to the observed CMR effect in doped LaMnO3 systems.