Colossal magnetoresistance manganites:: importance of the cooperative phenomena

After more than ten years of intensive studies on CMR manganites, the numerous results that have been obtained revealed an unpredicted richness of their chemistry and physics. In particular, the possibility to chemically tune the competition between the different ordering parameters linked to the degrees of freedom of spin, charge and lattice has allowed the creation of an infinite combination of compounds with remarkable properties. This point is illustrated by several examples based on half-doped compositions, i.e. for Mn3+/ Mn4+ ratio close to 1, for which substitutions at the Mn site allow the amounts of antiferromagnetic charge ordered and ferromagnetic charge delocalized phases to be balanced. Special attention is paid to the induced abrupt magnetization jumps. Additionally, the compositions involving a majority of tetravalent manganese are also very attractive. Taking into account their lower amount of Jahn-Teller Mn3+ cations, different physics is observed, including metallicity close to CaMnO3 or robust charge/orbital ordered antiferromagnetic structures for sufficient amounts of trivalent manganese. A second section is devoted to these electron rich manganites.