Angular dependence of tunneling magneto resistance in La0.7Sr0.3MnO3 step-edge junctions

La0.7Sr0.3MnO3 (LSMO) tunneling magnetoresistance (TMR) junctions have been fabricated on step-edge (00 1) SrTiO3 substrates with a high step-edge angle. In the measurement of magnetoresistance (MR) ratio versus external magnetic field H, butterfly-like MR curves are clearly observed. The MR(H) curves vary with theta, the angle between the applied magnetic field and the current direction in the substrate plane, showing anisotropic MR properties. A much broader MR(H) response is observed for the configuration of H perpendicular to the substrate plane. Additionally, the maxima-M R field H-p almost coincides with the coercive field If. for theta < 60 degrees but obeys a different form from H-c(theta). The high-field junction resistance shows an intrinsic sin(2) theta angular dependence, while the low-field resistance shows all extrinsic cos(4 theta) angular dependence. The distinctive features are mainly due to the induced magnetization anisotropy in the artificial steps of grain boundaries. (C) 2005 Elsevier B.V. All rights reserved.