The effects of tungsten concentration on crystalline structure and perpendicular magnetic anisotropy of Co-W films

In this study, Co-W thin films deposited by DC magnetron sputtering were demonstrated to be perpendicular magnetic anisotropic with large magnetocrystalline anisotropy energy (MAE). Thermodynamic calculations based on Miedema's semi-empirical model have been used to estimate the phase in this binary alloy system. Based on the thermodynamic calculations results, a series of Co-W thin films were deposited on amorphous Ta underlayer with different tungsten concentrations. According to the X-ray diffraction results, the crystal structure of Co-W thin films is consistent well with that of thermodynamic calculations. Large MAE of Co-W thin films can be obtained with K_u over 2.1 × 10⁵ J/m³ after vacuum annealing. The perpendicular coercivity (H_c) of Co-W thin film reaches 9.1 × 10⁴ A/m. Therefore, the Co-W thin film is considered as a potential choice of high-density magnetic recording media materials.