High Frequency Properties Of Co-based Soft Magnetic Thin Films

In recent years, with the developing of electronic components towards the direction of the miniaturization, high-frequency, and integrated materials, the foundation of electronic components was put forward higher requirements. In order to meet the needs of magnetic devices, the soft magnetic thin films with high permeability and high frequency has become the latest hot area of research of magnetic materials. The dynamic response of magnetic materials is of fundamental interest and is essential for various applications in modern magnetic storage technology. In order to achieve ultrafast data rates the magnetization reversal process has to be controlled to a maximum degree. This technological demand has also led to a revival in the research of fundamental aspects of magnetic properties as anisotropy and saturation magnetization, even more the modification of the effective damping parameter.Co-Zr films with designable in-plane uniaxial magnetic anisotropy have been prepared by oblique sputtering at room temperature. It has been found that the introduction of a small amount of Zr into obliquely deposited Co films results in excellent soft magnetic properties-1 Oe and high frequency responses (resonance frequency over 4.3 GHz). We have qualitatively explained that such an optimization comes from the enhancement of exchange coupling between the Co grains in the films by using the random anisotropy model. Thus, the magnetocrystalline anisotropy of grains can be suppressed and the'obliquely induced' anisotropy can become dominant in determining the static and dynamic properties of the obliquely deposited films. Therefore, films with designable static and dynamic properties can be easily obtained by controlling the deposition angles.Co-Nb-Nd soft magnetic thin films have been prepared on Si substrates. Strong enhancement of the damping parameter which is one key materials parameter that controls the dynamic response and the full width at half maximum of the imaginary permeability spectra were observed when Nd element was doped. The fitted value of the damping parameter for (Co0.85Nb0.15)93.6Nd6.4 film is around 0.1, which is almost one order larger than that 0.015 of (Coo.85Nbo.15)100 film.