CMR properties of Cr-doped Mn(IV)-rich manganites Ca1-xSmxMnO3

A systematic study of the doping of the manganese site with chromium in the charge ordered Mn(IV)-rich perovskites Ca1-xSmxMnO3 (0.15 less than or equal to x less than or equal to 0.5) has been performed. Whatever x, the charge ordering disappears for various chromium levels (2-13% Cr). By Cr doping, a ferromagnetic semimetallic component is induced at the expense of the antiferromagnetic state, at low temperature. An important feature deals with the expansion of colossal magnetoresistance (CMR) in all the diagram Ca1-xSmxMnO3 in the range 0.15 less than or equal to x less than or equal to 0.50. This spectacular ability of chromium to induce CMR and ferromagnetism has been extended to other lanthanides, i.e. Eu, Gd and Ho, showing the influence of the A-site average size. Moreover, this study demonstrates that the charge ordering is the most stable for manganese valency close to 3.70. (C) 1998 Elsevier Science B.V. All rights reserved.