Condensed Matter Seminars

Recently, doped manganites have been studied extensively due to various unusual phenomena observed in the system, such as the colossal magnetoresistance effect which is associated with a metal-insulator transition. Although a fundamental understanding of the system is not yet available, it is well known experimentally that spin, charge, and lattice degree of freedom are strongly coupled. We have studied epitaxial ultrathin manganite films in which bi-axial lattice distortion is imposed due to the lattice strain. Two anomalous effects are found which are not present in single crystals. One is unusually large low field magnetoresistance effect occurring only in compressively strained thin films and the other is giant anisotropic magnetoresistance. The details of the results will be presented and these results are not yet explained using existing models.