Abstract:
The application of the crystal curvature technique for stress measurements at surfaces and in films is presented. The contributions of surface stress, epitaxial misfit, film morphology and film magnetization to the measured stress are elucidated. It will be shown that oscillatory variations of the film roughness during layer-by-layer growth will also induce respective changes of the film stress with a monolayer period. The correlation between film strain and magnetic anisotropy is discussed in terms of the magneto-elastic coupling, which is well known as the driving force for 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. The magnetic anisotropy is also influenced by adsorbates. We find an hydrogen-induced switching of the easy magnetization direction in Ni monolayers from in-plane to out-of-plane, which occurs reversibly with respect to the hydrogen partial pressure in the gas phase around the sample, and we discuss the present understanding of this effect.