Thermal stability in perpendicular recording media

Magnetic and structural properties of CoCrPt based perpendicular recording media required to achieve both high thermal stability and low-noise performance are discussed, based on experimental results obtained using a pulse magnetometer. Experimental and theoretical analysis reveal that for CoCrPt based media of 20 nm thickness having the thermal stability factor KuV/(kT)approximate to 80, the maximum achievable value of the ratio of remanence coercivity to anisotropy field of grains, H-r/H-k is similar to0.35. Furthermore, in order to realize a large squareness M-r/M-x of nearly 1.0, which is required to resist the thermal agitation effect at low recording density, we find that the value of perpendicular magnetocrystalline anisotropy. K-u needed to be more than three times larger than 2 piM(s)(2). X-ray diffraction patterns suggested that the suppression of structural imperfections in the HCP structure, particularly in the initial growth layer, is the key issue to induce larger K-u value in the CoCrPt based media. (C) 2001 Elsevier Science B.V. All rights reserved.