Magneto - Electronic Phase Separation in Doped Perovskite Cobaltites

Jing Wu, University of Minnesota

Magneto-electronic phase separation refers to the presence of multiple magnetic and electronic phases within a material that is chemically homogeneous. It is very common in oxides and has been related to their most exciting properties such as superconductivity and colossal magnetoresistance (CMR). In this work, phase separation in the perovskite La_1-xSr_xCoO₃ was investigated comprehensively by conventional magnetometry, and electrical measurements as well as Small Angle Neutron Scattering (SANS), Nuclear Magnetic Resonance (NMR) and Transmission Electronic Microscopy (TEM). All the work leads to a consistent picture based on short range ferromagnetic ordering and intrinsic magnetic phase separation. The consequences of this intrinsic nanoscale phase separation were probed. The formation of FM clusters in a non - FM matrix results in an intergranular giant magnetoresistance effect, glassy transport phenomena, and a percolation threshold of x = 0.18.

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