Comparison between different methods of determining anisotropy constants of thin film media

The magnetic anisotropy K_u value of Co₈₁Cr ₁₅Ta₄ polycrystalline thin film medium was determined by using the 45 degree magneto-torque and the rotational hysteresis methods and compared with those of Co-Cr-Ta single crystal films with different Cr contents. The anisotropy field H_k of polycrystalline specimen determined by the rotational hysteresis method is confirmed to be underestimated. The K_u of the Co-Cr-Ta polycrystalline film determined by using the 45 degree magneto-torque method showed a reasonable agreement with that estimated from the single crystal specimen by taking into account of the Cr segregation in the polycrystalline grains