Improvement of soft magnetic properties of CoFeSiB thin film by external magnetic field and Zr addition

Co40Fe17Si32B11 thin film (150 nm) was deposited by using an RF magnetron co-sputtering system on a Si (100) substrate. A self-designed substrate holder, including various hard magnets arranged around the substrates, was utilized so that various external magnetic fields could be applied to the Si substrates during the film deposition. By the effect of this deposition field, the applied field during the sample deposition, the squareness of the CoFeSiB thin film was significantly enhanced. From the angular analysis of the magnetic hysteresis curves from easy (parallel to external magnetic field) to hard (perpendicular to external magnetic field) direction of magnetization, it can be deduced that Co and Fe atoms were magnetically arranged to the easy magnetization axis by an external magnetic field which was induced during deposition. Also, the compositional cluster size of the CoFeSiB thin film was remarkably reduced by Zr addition, causing a decrease in the value of coercivity. These results suggest that apparent magnetic anisotropy was achieved, and the soft magnetic property of the CoFeSiB thin film was remarkably enhanced by the combination of the deposition field and Zr addition.