Correlation of fluctuation field and temperature coefficient of coercivity in a CoCrPtB thin film

Abstract The effect of the ratio of fluctuation field ( H f ) to coercivity ( H c ) on the temperature coefficient of coercivity [ α ( H c )] was investigated for Co 55 Cr 15.5 Pt 28 B 1.5 /Co 63 Cr 37 /Cr, Co 69 Cr 19 Pt 9 Ta 3 /Cr, and Co 86 Cr 10 Ta 4 /Cr thin films (longitudinal recording media) with very small average grain volume ( V phy ). α ( H c ) increases markedly with increase in temperature between near 250 and 350 K for Co 55 Cr 15.5 Pt 28 B 1.5 /Co 63 Cr 37 /Cr thin films. α ( H c ) is approximately proportional to the ratio H f / H c for all thin films, as in the case of advanced data backup tapes prepared from ultrafine particles. α ( H c ) and the ratio H f / H c increase as V phy decreases. Smaller H f / H c values are necessary for small α ( H c ) values, which is very important for the thermal stability of high-density recording media with very small V phy .