Temperature Dependence of the Magnetization Reversal of Thin-Film Longitudinal Magnetic Recording Media

摘要

As longitudinal magnetic recording media approach the superparamagnetic limit, temperature-dependent effects are becoming ever more important. This work reports an unexpected temperature dependence for the Sharrock stability parameter S typically given as K_(u)V/k_(B)T, where K_(u) is the unixial anisotropy, V the switching volume, k_(B) is Boltzmann's constant, and T the temperature. Temperature-dependent vibrating sample magnetometer measurements were made of the saturation and remanent magnetization M_(s) and M_(r), remanent coercivity H_(cr), and K_(u). The Sharrock equation was used to calculate S, and the time-independent switching field H_(o) of representative longitudinal recording media. Instead of the product Sk_(B)T decreasing proportionally to K_(u) or H_(o) with increasing temperature as initially expected, we find Sk_(B)T decreases at approximately half this rate.