Inducing in-plane uniaxial magnetic anisotropies in amorphous CoFeB thin films

• Published in: Journal of magnetism and magnetic materials 2023-11, Vol.585, p.171015, Article 171015
• Main Authors: Scheibler, S., Yildirim, O., Herrmann, I.K., Hug, H.J.
• Format: Article
• Language: English
• Subjects: In-plane anisotropy; Magnetic thin films; Obliquely deposited seed layer
• ISSN: 0304-8853
• DOI: 10.1016/j.jmmm.2023.171015

Controlling the magnetic anisotropy of thin magnetic films with in-plane magnetization is of highest relevance particularly for magnetic field sensors. Here, the origin and magnitude of the in-plane magnetic anisotropies of ferromagnetic Co20Fe60B20 films with obliquely sputter-deposited Ta-seed layers are investigated. Uniaxial in-plane anisotropy constants in the range of a few kJ/m3 up to about 25 kJ/m3 become accessible. We find that the anisotropy is predominantly determined by an surface rather than the bulk term. However, the magnetostatic effects arising from the measured directional roughness of the Ta seed cannot fully account for the observed anisotropy, indicating the existence of an additional origin of the anisotropy arising from the oblique sputtering. Further, we find that the anisotropies of films deposited with normal incidence in an applied magnetic field are about an order of magnitude weaker. Overall, this work shows that oblique sputtering offers a strategy to induce in plane anisotropies of up to 25 kJ/m3 in CoFeB, however, at the expense of larger Ta seed thickness. •Tunable in-plane anisotropies in Co20Fe60B20 films on obliquely deposited Ta-seeds.•Interface-anisotropy with contributions from roughness-induced magnetostatic effects.•In-plane anisotropies up to 25 kJ/m3 albeit only at larger Ta-seed thicknesses.