Thin films of perovskite manganite La↓(0.7)Ca↓(0.3)MnO↓(3) were grown epitaxially on SrTiO↓(3)(100), MgO(100) and LaAlO↓(3)(I00) substrates by the pulsed laser deposition method. Microscopic structures of these thin film samples as well as a bulk sample were fully determined by x-ray diffraction measurements. The unit cells of the three films have different shapes, i.e., contracted tetragonal, cubic, and elongated tetragonal for SrTiO↓(3), MgO, and LaA1O↓(3), respectively, while the unit cell of the bulk is cubic. It is found that the samples with a cubic unit cell show smaller peak magnetoresistance at low fields (#1 T) than the noncubic ones do. The present result demonstrates that the magnetoresistance of La↓(0.7)Ca↓(0.3)MnO↓(3) at low fields can be controlled by lattice distortion via externally imposed strains. # 1997 American Institute of Physics. S0003-6951(97)03633-4
展开▼
