Magnetoresistance effect in layered-perovskite La2-2xCa1+2xMn2O7 thin films

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