Role of Nb content in tailoring the microstructure and magnetic anisotropy of soft magnetic W/CoFeB alloy thin films prepared with varying the substrate temperature

The work describes the role of Nb addition on the magneto-structural properties of magnetron sputtered Si/SiO2/W/(CoFeB)(1-x)Nb-x (x = 0, 3, 5 and 10) metal metalloid alloy thin films. Films were grown at substrate temperature (T-s) of RT, 300 degrees C and 500 degrees C to realise the influence of Nb content in the amorphous and nanocrystalline states of (CoFeB)(1-x)Nb-x thin films. RT deposited films are soft magnetic (coercivity (H-c) <= 10 Oe), exhibits amorphous microstructure and display a well-defined uniaxial magnetic anisotropy (UMA) in the film plane. At 300 degrees C, devitrification occurs, and the film (x = 0) becomes partially crystalline with precipitation of FeCo nano-crystals, and UMA nearly disappears. With increasing Nb content, the mean grain size and amount of FeCo nano-crystals decreases, and partially crystalline CoFeB films transform to a completely amorphous microstructure with the simultaneous appearance of in-plane UMA and systematic improvement in soft-magnetic nature (H-c decreases from similar to 22-5 Oe). Nb addition on at Ts=500 degrees C results in grain growth inhibition and magnetically isotropic (CoFeB)(1-x)Nb-x films (except x = 3). The present study demonstrates that thermally stable amorphous CoFeB films with desired soft magnetic properties can be prepared by appropriate selection of Nb content and suitable growth temperature. (c) 2022 Elsevier B.V. All rights reserved.

Automated summary

The study investigates the influence of Nb addition on the magneto-structural properties of magnetron sputtered Si/SiO2/W/(CoFeB)(1-x)Nb-x metal metalloid alloy thin films. The results show that increasing Nb content leads to a transition from amorphous to nanocrystalline structure, accompanied by the emergence of in-plane magnetic anisotropy and improved soft-magnetic behavior.