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The microwave-assisted switching properties of a CoCrPt–TiO2 granular perpendicular medium are investigated by detecting the anomalous Hall effect. We improved the device structure to be able to generate a linearly polarized microwave field of 950 Oe without a significant increase in temperature. Coercivity decreases linearly with increasing microwave frequency and the microwave assistance effect is most enhanced by the application of microwaves of 18 GHz frequency with a coercivity reduction ratio of 55%. more...

The magnetic properties and microstructure of triple C/CoCrTa/Ti perpendicular recording films have been studied. Magnetic measurements show that the optimal thickness of Ti underlayer is 40 nm and that of CoCrTa is 35 nm. The optimal value of substrate temperature is found to be 400°C. A suitable Ti underlayer causes a magnetic layer to have a near-perfect hcp texture, with Co grains in the (002) preferred orientation. The film with needle-like grains is more suitable for perpendicular recording films. more...

The dynamic performance of heat assisted magnetic recording (HAMR) on different media is investigated. Signal and signal-to-noise ratio enhancement are achieved in high coercivity perpendicular media with the aid of laser heating. Linear recording density is increased while saturation write current is lowered. Trailing field partial erasure is observed in lower coercivity media with a ring head, which causes signal reduction with increasing write current or application of a laser. Precautions should be taken against partial erasure in overall recording system optimization of HAMR in order to achieve ultrahigh recording density. more...

The slopes of the M–H loop of perpendicular magnetic recording media were estimated by micro-magnetic simulation for various inter-grain exchange couplings, grain aspect ratios and inter-grain spacings. The slope of the M–H loop depends not only on inter-grain exchange coupling but also on grain aspect ratio and inter-grain spacing. The simulation revealed that the required head field decreases with increasing inter-grain exchange coupling. The optimum value of the slope was slightly larger than 1.0 for compromising resolution and SNR by changing the inter-grain exchange coupling. The simulation results also indicated that the inter-grain spacing improves both resolution and SNR. more...