Abstract
(Fe65Co35)N soft magnetic thin films were prepared by reactive RF magnetron sputtering with the sputtering power of 100 W on thermally oxidized Si substrate in various nitrogen partial pressures (PN2). A strong uniaxial in-plane magnetic anisotropy with the easy-axis coercive field as low as 1∼2 Oe was observed in films grown at PN2 in the range from 3.3% to 5.5%. The saturation magnetizations for those films were about 20 KG. Outside this range, almost isotropic magnetization curves were observed. Vector network analyzer and grounded coplanar waveguide were used to measure the ferromagnetic resonance (FMR) signals up to 25 GHz. The FMR signals were detected only in anisotropic films and their FMR frequencies were well fit to the Kittel formula. The obtained g-values and damping parameters at magnetic fields >20 kOe for films grown at PN2 of 3.3%, 4.8% and 5.5% were 1.96, 1.86, 1.92 and 0.0055, 0.0047, 0.0046, respectively. This low damping factor qualifies FeCoN thin films for high-frequency applications.
Highlights
FeCoN thin films are a promising material for high frequency applications because of high saturation magnetization and low coercivity since nitrogen in the films plays an important role in the microstructure of FeCoN.[1,2,3,4,5,6,7,8,9] Magnetic characteristics of saturation magnetizations 4πMs above 20 kG, coercivities of only a few Oe, and high uniaxial in-plane anisotropy have been typically obtained when the nitrogen content is optimized
FeCoN film prepared with Permalloy seed layer showed a ferromagnetic resonance (FMR) frequency over 2 GHz at zero-bias field, which is very promising for applications in write heads and integrated inductors.[1]
We show that magnetic properties and high frequency characteristics of FeCoN thin films are sensitive to the nitrogen partial pressure percentage (PN2) of sputtering gas
Summary
FeCoN thin films are a promising material for high frequency applications because of high saturation magnetization and low coercivity since nitrogen in the films plays an important role in the microstructure of FeCoN.[1,2,3,4,5,6,7,8,9] Magnetic characteristics of saturation magnetizations 4πMs above 20 kG, coercivities of only a few Oe, and high uniaxial in-plane anisotropy have been typically obtained when the nitrogen content is optimized. FeCoN film prepared with Permalloy seed layer showed a FMR frequency over 2 GHz at zero-bias field, which is very promising for applications in write heads and integrated inductors.[1] Magnetic ripples in the film by inhomogeneity of the substrates in strains can lead to change of magnetic properties. FeCoN thin films sputtered on the flexible Kapton substrate showed ultrawide frequency linewidth, which was explained by the dispersed magnetic ripples due to the flexible substrates.[3] Control of the sputtering gas pressure can adjust the stress of film which has been shown to be effective in tuning the damping parameters.[9] In this work, we show that magnetic properties and high frequency characteristics of FeCoN thin films are sensitive to the nitrogen partial pressure percentage (PN2) of sputtering gas
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