Improving the high-frequency magnetic properties of as-deposited CoFe films by ultra-low gas pressure.

CoFe films without buffer layers were deposited at different ultra-low argon pressures ranging from 0.085 to 0.847 mTorr. This pressure range was one to two orders lower than the normal sputtering pressure. As a consequence, the static magnetic properties, including coercivity and magnetic anisotropy field, were improved with decrease argon pressure. The high-frequency permeability spectra showed that the resonance frequency and the damping factor of the films also reached optimal values at ultra-low pressure. Basing on atomic force microscopy observations, we attributed the excellent properties to the improved morphologies of the films and released internal stress. [ABSTRACT FROM AUTHOR]