Evolution with thermal annealing of magnetic anisotropy in FeCoB thin film interfaced with Mo layers

Highlights: • Effect of thermal annealing on FeCoB films sandwiched between two Mo layers has been studied. • Uniaxial magnetic anisotropy of as-deposited film disappears with annealing at 300 °C. • Annealing at still higher temperature causes anisotropy to reappear. • Grazing incidence XRD has been used to characterize the associated structural changes. • Variations in internal stresses and grain texture cause the observed changes in anisotropy. Evolution of magnetic properties of thin FeCoB films sandwiched between two Mo layers has been studied as a function of thermal annealing at different temperatures. The as-deposited film exhibits a uniaxial magnetic anisotropy. With thermal annealing up to 300 °C, anisotropy gradually decreases while coercivity exhibits a significant increase. Uniaxial anisotropy reappears after annealing at 400 °C. In order to understand the origin of magnetic anisotropy in the film, in-plane and out-plane X-ray diffraction measurements have been done using Hard X-ray beamline BL-11 of INDUS-2. It is found that with thermal annealing the film exhibits significant changes in grain texture as well as internal stresses. Variation in grain texture in the film is expected to be the main cause for observed magnetic anisotropy.