(Gd,Tb,Dy)FeCo磁光薄膜的磁性及記錄特性

Abstract

One of the most promising methods to simultaneously improve the areal density/capacity, data rate, and access time of magneto- optical disks is to reduce the required bias field (Hb). In this thesis, the required Hb of (Gd,Tb,Dy)FeCo films were correlated to the subnetwork exchange coupling in single-layered films and the inter-layered exchange coupling in exchange-coupled double- layered (ECDL) films. When the recorded magnetic domain size (about 0.5 mm) is less than the focused laser spot size (about 1 mm),The magnetic properties and the recording characteristics of single-layered (Dy,Tb)FeCo films were analyzed by mean field modeling. The experimental results showed that the required Hb and the domain wall mobility of Dy23.7(Fe87Co13)76.3 films are about 1/2 ~ 1/3 and 2 ~ 3 times those of Tb23.1(Fe90Co10)76.9 films during thermo-magnetic recording. Accordingly, the required Hb of a (Dy,Tb)FeCo film is inversely proportional to its domain wall mobility which was found to be determined by the anisotropy disperThe magnetic properties of single-layered sperimagnetic films are also governed by a finite exchange coupling coefficient (l), because of its dependence on the subnetwork coupling strength. From the study of a series of (Dy, Tb)FeCo films, it is found that l is mainly determined by the concentration of the rare earth components. The exchange integral between rare earth and transition metal subnetworks can be derived from the measured l so that the number of uncertain parameters for mean field modeling is redECDL films were adopted to simultaneously increase the areal density of MSR media by using center aperture detection (CAD) scheme and the switching field sensitivity by capping effect. The temperature dependence of interface wall energy was found to affect the recording/ playback characteristics of ECDL MSR CAD disks considerably. The interface wall energy, required by the stabilization of recorded marks, the aperture function for MSR CAD readout, and the capping effect to lower switching field, can be satis