Inhomogeneous magnetism in La-doped CaMnO3.: I.: Mesoscopic phase separation due to lattice-coupled ferromagnetic interactions -: art. no. 134439

A detailed investigation of mesoscopic magnetic and crystallographic phase separation in Ca1-xLaxMnO3, 0.00less than or equal toxless than or equal to0.20, is reported. Neutron powder diffraction and dc-magnetization techniques have been used to isolate the different roles played by electrons doped into the e(g) level as a function of their concentration x. The presence of multiple low-temperature magnetic and crystallographic phases within individual polycrystalline samples is argued to be an intrinsic feature of the system that follows from the shifting balance between competing ferromagnetic (FM) and antiferromagnetic (AFM) interactions as a function of temperature. FM double-exchange interactions associated with doped e(g) electrons are favored over competing AFM interactions at higher temperatures, and couple more strongly with the lattice via orbital polarization. These FM interactions thereby play a privileged role, even at low e(g) electron concentrations, by virtue of structural modifications induced above the AFM transition temperatures.