2015 Volume 39 Issue 5 Pages 196-204
Fe-B alloy films of 40 nm thickness are prepared on MgO(001) single-crystal substrates using alloy targets of Fe100–xBx (x = 0, 8, 13, 18, 25 at. %) by varying the substrate temperature from room temperature to 600 °C. The structure is systematically investigated by reflection high-energy electron diffraction, X-ray diffraction, and cross-sectional high-resolution transmission electron microscopy. (001) single-crystal films with bcc-based disordered A2 structure epitaxially grow at the investigated substrate temperatures for the B contents less than 8 at. %. On the contrary, the Fe87B13, the Fe82B18, and the Fe75B25 films respectively deposited at temperatures lower than 200, 400, and 600 °C involve amorphous. The crystallization temperature increases with increasing the B content. The surface roughness increases with increasing the substrate temperature. Island-like surfaces are formed for the films deposited at elevated temperatures. The (001) films show four-fold symmetries in in-plane magnetic anisotropy, whereas the amorphous films show isotropic magnetic properties. The coercivity increases with increasing the substrate temperature due to that domain wall motion is suppressed by the crevasses in the films existing between large islands.