We have developed a new perpendicular thermo-magnetic recording method coupled with magnetic flux detection. The resolution is substantially improved by flux detection. Compared to the latest magneto-optical disk drives, the carrier-to-noise ratio of a reproduced signal is 5 dB higher, and the recording density reaches 8.3 Gbit/inch2. Moreover, this recording method has a good affinity to near-field optics, and it is an effective technique for attaining a higher density beyond the super-paramagnetic limitation in longitudinal magnetic recording.

The distribution of the optical near-field generated by a probe with a wedge-shaped metallic plate was calculated using a finite difference time domain method. The dependence of the distribution on the size and the material of the metallic plate was calculated, and it was shown that a strong optical near-field was generated at the apex of the metallic plate when the size and the material were optimized so that a surface plasmon was excited in the metallic plate. The influence of the recording medium was also calculated. The resonance wavelength shifted toward a longer wavelength and the decay length of the optical near-field increased when the recording medium was placed near the probe. The spot size calculated on the surface of the recording medium was 30 nm, and the efficiency (defined as the ratio between the power of the optical near-field at the surface of the recording medium and that of the incident light) was about 20% when the spacing between the probe and the recording medium was 10 nm. The near-field distribution for a probe with two metallic plates was also calculated, and it was shown that a strong optical near-field was generated between the apices of the metallic plates when the plasmon was excited in the metallic plates.

We studied a thermally assisted magnetic recording on flux-detectable RE-TM media. This recording scheme has a close affinity with near-field optics such as solid immersion lens (SIL) optics and scanning near-field optical microscope (SNOM)-type optics. The requirements for high-density thermo-magnetic recording and a novel near-field optical head were discussed.Index Terms-Magneto-optical disk, near field, RE-TM, thermo-magnetic recording.

In our comprehensive crystallographic investigation of the La 1.85−x Pr x Sr 0.15 CuO 4 system (0 x 1.85), we observe the structural phase evolution T → T+T → T with increasing Pr substitution. In the La 1.85−x Pr x Sr 0.15 CuO 4 system, the suppression of the superconductivity is not related to the interaction of the Pr ions with the O ions in the CuO 2 plane which leads to the localization of hole carriers. It is the removal of apical oxygen from the (La, Pr)-O plane that is responsible for the suppression of the superconductivity.