Tailoring structural and magnetic viz. static and dynamic properties of soft magnetic CoFeB film with Ta incorporation

Present study provides an insight of tailoring magnetic properties (static and dynamic) driven by structural modifications, with controlled incorporation of Ta in soft magnetic CoFeB films. Unlike conventional thermal annealing, stress induced in-plane uniaxial magnetic anisotropy of CoFeB have observed to be release with incorporation of Ta, as confirmed from in-plane rotation dependent magneto-optical Kerr effect (MOKE). Increasing atomic percent of Ta in CoFeB is accompanied with decreasing saturation magnetization of soft-magnetic layer and film densification, as confirmed from polarized neutron and X-ray reflectivities. Ferromagnetic resonance (FMR) confirms the reduction of effective magnetization of the samples with Ta incorporation, with rise of damping parameter because of increasing magnetic inhomogenities. Further, the effect of vacuum annealing on these films has been investigated. Post annealing measurements suggest rapid elimination of magnetic anisotropy for Ta doped CoFeB films. Annealing at a temperature beyond CoFeB crystallization temperature results in an increase of magnetization, relative to as-prepared samples, amplitude of which modifies with incorporated Ta concentration. Such enhancement is accompanied with the structural changes as confirmed from X-ray diffraction (XRD) measurements, resulting an increase of magnetic coercivity. The results are important in view of tailoring the functional properties of CoFeB films for wide range of applications. (C) 2022 Published by Elsevier B.V.

Automated summary

This study provides an example of tailoring magnetic properties by structural modifications with controlled incorporation of Ta in soft magnetic CoFeB films. Unlike conventional thermal annealing, the stress-induced in-plane uniaxial magnetic anisotropy of CoFeB is released with the incorporation of Ta. The increase in atomic percent of Ta in CoFeB leads to a decrease in the saturation magnetization of the soft magnetic layer and film densification. Ferromagnetic resonance confirms the reduction of effective magnetization and the increase in damping parameter due to the presence of Ta. Vacuum annealing rapidly eliminates the magnetic anisotropy in Ta-doped CoFeB films, and annealing at a temperature beyond the CoFeB crystallization temperature increases the magnetization and magnetic coercivity.