Transport and magnetic properties of electron-doped manganites CaMn1-xSbx03

We report transport and magnetic properties of electron-doped manganites CaMn1-xSbxO3. The substitution of Sb5+ ion for Mn 4+site of the parent matrix causes one-electron doping with the chemical formula CaMn4+1-2xMn3+xSb5+x03. Single phase samples (x = 0.02, 0.05, 0.08 and 0.1) are prepared with a solid-state reaction method. Upon increasing the doping level of Sb, the resistivity is suppressed at high temperatures, accompanied by carrier doping. However, it is strongly enhanced at low temperatures because the presence of the Sb ion prevents moving of carriers on the MnO network. Seebeck coefficient of the samples studied shows a negative value over a whole range of temperatures, indicating the electron doping. An anomalous diamagnetic behavior is observed at x = 0.02 0.05 and 0.08, as it has been reported in the V doped manganites. These findings are close to the variation of eg orbital state due to the local lattice distortion associated with the Sb doping.