MAGNETORESISTANCE EFFECT IN LAYERED-PEROVSKITE LA2-2XCA1-FILMS(2XMN2O7 THIN)

Ferromagnetic thin films of La2-2xCa1+2xMn2O7 (x=0.3) with a tetragona l Sr3Ti2O7-type layered perovskite structure have been deposited on Mg O and SrTiO3 (001) substrates by magnetron sputtering. The epitaxial t hin films in this study have the a-axis normal orientation with 90 deg rees domains having the a/c boundaries in the film plane. These thin f ilms exhibit highly enhanced magnetoresistance (MR) effects (MR ratio Delta rho/rho(0) of -93% at mu(0)H=1T) compared with those reported fo r thin films of cubic ferromagnetic perovskite with isotropic Mn-O net works. These MR behavior can be explained by taking account of the two -dimensionality and anisotropy of the Mn-O networks in the ferromagnet ic layered perovskites.