Thermal agitation of magnetization in CoCrPt 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 K/sub u/V/(kT)/spl ap/80, the maximum achievable value of the ratio of remanence coercivity to anisotropy field of grains, H/sub r//H/sub k/, is /spl sim/0.35. Furthermore, if the strictest condition of demagnetizing factor, 4/spl pi/, for perpendicular media is assumed, in order to realize a large squareness M/sub r//M/sub s/ of nearly 1.0, which is required to resist the thermal agitation effect, we find that the value of perpendicular magnetocrystalline anisotropy, K/sub u/, has to be more than 3 times larger than 2/spl pi/M/sub s//sup 2/.