Stress, Strain and Magnetic Anisotropy: All Is Different in Nanometer Thin Films
The application of the crystal curvature technique for stress measurements at surfaces and in films is presented. Important aspects regarding sample clamping and elastic anisotropy are elucidated in view of a quantitative stress analysis. Combined stress measurements and structural characterizations are mandatory to obtain a meaningful interpretation of the stress data. The in-situ combination of surface X-ray diffraction with stress measurements indicates a previously unknown substantial distortion of a W(110) surface layer upon Ni coverage, and the decisive role of this substrate relaxation for the stress state is discussed. The magnetization-induced stress in epitaxial layers is measured to derive the magneto-elastic coupling coefficients, which drive the magnetostriction of bulk samples. It is found that even a subtle film strain in the sub-percent range leads to a drastically modified magneto-elastic coupling in the films as compared to the respective bulk value. The implication of non-bulk like magneto-elasticity for the magnetic anisotropy of strained films is emphasized, and recent progress in the theoretical description of the strain-dependent modification of the magneto-elastic coupling is acknowledged.
KeywordsMagnetic Anisotropy Stress Measurement Stress Change European Synchrotron Radiation Facility Elastic Coupling
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