Surface Magneto-Optical Kerr Effect Study of Magnetization Reversal in Epitaxial Fe(100) Thin Films

Abstract

Surface Magneto-optic Kerr Effect (SMOKE) technique is used to study the magnetization rotation in single crystalline Fe thin films, deposited onto MgO (100) substrates by magnetron sputtering, with thicknesses, tFe, varied within the range from 70 Å to 250 Å. The crystalline structure and epitaxial relation are determined employing X-ray diffraction (XRD). The SMOKE loops are interpreted in the framework of a phenomenological model for coherent rotation of the magnetization. The switching behavior of these films is characterized by two different reversal regimes. In films with thicknesses less than a critical value (tFe<tc), there is a superposition of the magneto crystalline anisotropy to an uniaxial in-plane anisotropy, and as a consequence the magnetization rotation is non-coherent with motion of Néel and Bloch domain walls. As the thickness is increased from the critical thickness, and the uniaxial anisotropy is overwhelmed by the magneto crystalline anisotropy, the magnetization reversal turns coherent with Bloch domain walls motion. The thickness dependence of all anisotropy constants follow a function of 1/tFe as expected for interface effects.