In-plane c-axis oriented barium hexaferrite films prepared by magnetron sputtering

In-plane c-axis oriented M-type barium hexaferrite (BaM) films were grown on a-plane sapphire (112̄0) substrates by radio frequency magnetron sputtering with ex-situ annealing. Oxygen in sputtering atmosphere played a critical role in the c-axis orientation growth of BaM films. With incorporation of 10% O2 during sputtering, in-plane c-axis highly oriented BaM films with high hysteresis loop squareness (Mr/Ms∼0.94) along in-plane easy axis and low Mr/Ms∼0.08 along in-plane hard axis was achieved. In contrast, films sputtered without O2 incorporation showed poor magnetic anisotropy and low hysteresis loop squareness along both directions. The oxygen induced formation of oriented hematite intermediate phase was found, which was supposed to be responsible for the in-plane orientation growth of BaM grains.

Graphical AbstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► In-plane c-axis oriented barium hexaferrite films are fabricated by sputtering. ► Oxygen in sputtering plasma is critical to the oriented growth of barium ferrite. ► Oriented α-Fe2O3 is formed prior to the formation of oriented barium ferrite. ► High remanence ratio (0.94) can be achieved with oxygen in sputtering plasma.