LOCAL DISORDER EFFECTS ON THE PRESSURE-DEPENDENCE OF THE METAL-INSULATOR-TRANSITION IN MANGANESE PEROVSKITES

We address the role of the local disorder created by substitutional io ns in L(2/3)A(1/3)MnO(3) oxides, on the pressure dependence of the Cur ie temperature dln T-C/dP. A number of manganites having distinct aver aged lanthanide R-0 radii and size variance sigma(2) have been prepare d and their resistivity measured up to 11 kbar. It is found that the m easured dln T-C/dP is mainly determined by R-0. However, materials hav ing larger local disorder display larger pressure sensitivity. It is p roposed that this results from partial suppression of the local disord er under pressure, and a model is developed to account for the experim ental data. (C) 1998 American Institute of Physics.