EPR Evidence for Premonitory Charge-Ordering Fluctuations in Nanomanganite Pr_(0.57)Ca_(0.41)Ba_(0.02)MnO_3

摘要

The competition between the colossal magnetoresistive (CMR) ferromagnetic (FM) and the charge ordered (CO) antiferromagnetic (AFM) ground states in doped perovskite rare earth manganites RE_(1-x)A_xMnO_3 where RE is a trivalent rare earth ion (Re = La, Nd, Pr,...) and A is a divalent alkaline earth ion (Ca, Sr,..) is an issue that is being studied intensely at present. Recently we have shown [1, 2] that by preparing these compounds in nanometric sizes (nanowires and nanoparticles) it is possible to change the ground state from charge ordered AF (in the bulk) to FM CMR.