Bandwidth dependence of the charge-order and Curie temperatures in manganese perovskites

We compare the variations of the charge-order (T-CO) and the Curie (T-C) temperatures in series of L(1-x)A(x)MnO(3) (L and A are trivalent lanthanide and divalent alkaline-earth cations, respectively; x = 1/2 and 1/3) perovskites when modifying the e(g) electron bandwidth W. This is accomplished by using appropriate cationic substitutions at the lanthanide position. It is found that T-CO decreases almost linearly with increasing R-0 (R-0 is the averaged size of the cations at the lanthanide position) as expected on the basis of steric effects on W. In contrast, TCR0 has a parabolic dependence, increasing Te as R-0 increases. We analyze this distinct behavior, and we suggest that it originates from the polaronic nature of carriers which produces notable effects on the observed T-C (W) dependence. [S0163-1829(99)02833-7].