Abstract
The external magnetic field characteristics were investigated for the exchange-coupled quadrilayered magento-optical film that was applied to the direct overwriting by light intensity modulation. The external field dependence in recording characteristics was studied through the temperature dependence of the reversal field and mechanism of the direct overwriting. In the direct overwriting by light intensity modulation, the upper limit of the external field existed due to the low process. Here the initializing process of the writing layer that is unique to the quadri-layered film did not participate in the lower limit of the external field. Wide external field margin was obtained for a practical use. So the effective fluctuation of the external field did not affect the recording laser power margin.
