Initializing process on direct overwrite method using exchange-coupled quadilayer magneto-optical film
A direct overwrite mechanism of the exchange-coupled quadri-layered film using light intensity modulation has been investigation. The initializing process in the overwrite mechanism was studied. It was found that the writing layer had two different coercivities depending on the magnetization state of its adjacent layers. The coercivity of the writing layer in the initializing process was lower than that of the single layer. Thus, the overwrite recording was achieved with good recording characteristics. How this phenomenon plays a critical role in the initializing process was clarified. It was also found that this process occurred well above room temperature. >
Magnetic Field Characteristics in the Quadri-Layered M-O Film with Overwritability
The authors investigated the external magnetic field characteristics of exchange-coupled quadrilayer magnetooptic film in direct overwriting by optical modulation. The external field dependence of the recording characteristics was studied through the temperature dependence of the reversal field and the mechanism of direct overwriting. In direct overwriting by optical modulation, an upper limit to the external field exists due to the "low" process. Here the process of initialization of the writing layer, unique to the quadrilayer film, did not affect the lower limit of the external field. A wide external field margin was obtained under conditions of practical use, and effective fluctuations in the external field did not affect the recording laser power margin.
Anomalous Magneto-optical Hysteresis Loops of Sputtered Gd-Co Films
Hysteresis loop anomaly in Gd-Co films has been studied by measuring magneto-optical Kerr loops at a temperature range from 20 to 60°C. Anomalous loops were observed at one surface of the films and in a certain temperature range. The other surface always gave normal loops. All the features of the observed anomalous loops can be explained by a magnetization gradient model along the film thickness.