Magnetostatic Coupling MSR with In-Plane Magnetization Films

Magnetically induced super resolution (MSR) with double (front and rear) masks was achieved using GdFeCo/GdFe/TbFeCo (readout/intermediate/memory) triple layer films. The duplication of information from the memory layer to the readout layer is done through the magnetostatic coupling. The front mask and the rear mask are formed by in-plane magnetization and by collapsing written domains, respectively, without applying external fields. The transition from in-plane to perpendicular magnetization was made sharper by introducing the intermediate layer. Using this MSR medium and a conventional optical head (λ=780 nm), carrier-to-noise ratio (C/N) of over 45 dB for a mark length of 0.40 µm and crosstalk of -38 dB for a 0.8 µm track pitch were achieved. However, during the readout process, the magnetostatically coupled MSR medium is much more sensitive to the disturbance of external fields than exchange-coupled MSR medium.