Journal of Magnetism and Magnetic Materials 246, 327 (2002)

M. Ziese, H. C. Semmelhack and P. Busch

Abstract

The magnetic anisotropy of epitaxial manganite La_0.7A_0.3MnO₃ films (A = Ca, Sr, Ba, ∇=vacancy) is studied as a function of tolerance factor. Within the film plane a biaxial magnetocrystalline anisotropy was observed with an anisotropy constant changing sign as function of doping: whereas La_0.7Ca_0.3MnO₃ and La_1−x□_xMnO₃ have [1 0 0] easy axes, La_0.7Sr_0.3MnO₃ and La_0.7Ba_0.3MnO₃ films were found to have [1 1 0] easy axes. This is related to a symmetry change of structural distortions with increasing tolerance factor. Films strained by the substrate show a large uniaxial magnetoelastic anisotropy along the film normal; the saturation magnetostriction was determined to λ₁₀₀=(3–6)×10⁻⁵