EFFECTS OF FE DOPING IN THE COLOSSAL MAGNETORESISTIVE LA1-XCAXMNO3

The effect of Fe doping (<20%) on the Mn site in;the ferromagnetic (x= 0.37) and the antiferromagnetic (x=0.53) phases of La1-xCaxMnO3 has be en studied. Upon doping, no appreciable structure changes have been fo und in either series. However, conduction and ferromagnetism have been consistently suppressed by Fe doping. Colossal magnetoresistance has been shifted to lower temperatures, and in some cases enhanced by Fe d oping. These results are not due to the strong lattice effects commonl y seen in doping of the La sites. Rather, replacement of Mn3+ by Fe3depopulates the hopping electrons, and weakens the double exchange. Th e effect of Fe doping can be explained in terms of the band structure. (C) 1997 American Institute of Physics.