Lattice distortion effects at grain boundaries in colossal magnetoresistive films

Summary form only given. The role of strain on the magnetic and magnetotransport properties of colossal magnetoresistance (CMR) films has been reported widely both experimentally and theoretically and it is now a well accepted phenomenon. Depending on the lattice mismatch between the film and the substrate, strain on the film varies leading to a significant modulation of the Curie temperature T/sub c/. Using local probes - magnetic force microscopy (MFM) and X-ray microdiffraction - we have studied lattice distortion effects at grain boundaries in epitaxial manganite films. Our key result is that at the grain boundaries the lattice distortion is relaxed, resulting in a modification of the magnetic properties compared to the grain interior. Our results are in agreement with previous speculations of the existence of a magnetically or electronically distinct region at grain boundaries inferred from intergrain spin-polarized transport measurements.