MAGNETOELASTIC COUPLING AND MAGNETIC-ANISOTROPY IN LA0.67CA0.33MNO3 FILMS

We report the results of magnetization measurements on pseudomorphic ( fully strained) c-axis oriented colossal magnetoresistance manganite t hin films grown by molecular beam epitaxy. We observe uniaxial magneti c anisotropy (hard axis/easy plane) with the easy plane being the film plane. Within the plane a weaker biaxial anisotropy is observed with [100] (Mn-O bond direction) easy axes. The magnetization dependence of the uniaxial anisotropy constant follows the predicted magnetization dependence of the magnetostriction constants within single-ion models indicating that the anisotropy energy is dominated by strain-induced a nisotropy from the lattice constant mismatch with the SrTiO3 substrate . These results indicate a magnetostriction constant lambda(100)approx imate to+7 x 10(-5), and an induced orbital moment of at least 0.02 mu (b)/Mn ion. We predict that by appropriate substrate selection an equi librium out-of-plane magnetization can be produced. (C) 1998 American Institute of Physics. [S0003-6951(98)01014-6].