In-plane grain boundary effects on the magnetotransport properties of La0.7Sr0.3MnO3-δ

C-axis oriented La0.7Sr0.3MnO3-delta (LSMO) films were fabricated on the top of SrTiO3/YBa2Cu3O7 grown on MgO (001) substrates. From x-ray phi-scan and planar transmission electron microscopy measurements, the LSMO layer in the LSMO/SrTiO3/YBa2Cu3O7/MgO heterostructure is found to have coherent in-plane grain boundaries with a predominance of 45 degrees rotations (between [100] and [110] grains) in addition to the cube-on-cube epitaxial relationship. Also, epitaxial LSMO/Bi4Ti3O12/LaAlO3 (001) and c-axis textured LSMO/Bi4Ti3O12/SiO2/Si (001) with random in-plane grain boundaries are introduced as the counterparts for comparison. The resistivity and magnetoresistance (MR) of LSMO layer were measured and compared. The low field MR at low temperature shows a dramatic dependence on the nature of the grain boundary. An attempt is made to interpret these results on the basis of correlation between the magnetic properties and grain structures. (C) 1998 American Institute of Physics.