Physics of high density recording thin film media established by ultra clean sputtering process

To achieve high density magnetic recording media through systematic experiments by applying the ultra clean sputtering process the following universal guiding principles are proposed: (1) H_c/H_k^grain ≈ 0.4 (isotropic), (2) to suppress the magnetostatic coupling effect due to the grain size reduction 4πM_s/H_k^grain < 1.0, (3) grain diameter < 10 nm, (4) (110), (100) preferred grain orientation of HCP crystallite, (5) for the improvement of D₅₀, tB_r < 50 Gμm, (6) for freezing the superparamagnetic effect due to grain size reduction vK_u^grain/kT ≥ 40, K_u^grain ≥ 3 × 10⁶ erg/cm³ (v: volume of magnetic grain, K_u^grain : magnetocrystalline anisotropy energy constant, kT: thermal energy).