No abstract

Shubnikov de Haas(SdH) oscillations have been measured for the semiconducting single domain SrTiO3 with Carrier concentration of 3.4×1018 cm-3 and 5.9×1018 cm-3. From the temperature dependence of the SdH amplitude, the cyclotron mass values are determined for the [001] and [110] magnetic field directions. We have found, from the angular dependence of the SdH oscillation, that there exist several branches of the frequencies among which the highest and lowest branches originate from the Fermi spheres at the Brillouin zone center, and the other ones from the extremal area which is interconnected through the magnetic breakdown tunneling paths. Energy band parameters based on the k p perturbation method are determined.

Ferromagnetic-film-coated carbon nanotube (CNT) probes were employed in a magnetic force microscope (MFM) observation. We succeeded in making a uniform ferromagnetic film on the CNT probes by improving the coating process and selecting materials. The performance of the CoFe-coated CNT probe was evaluated in ultra-high-density perpendicular magnetic storage media with densities from 600 to 1100 k flux changes per inch (FCI). The magnetic domain structure of the magnetic storage media was clearly observed up to 1100 kFCI. The ultimate lateral resolution of the newly developed MFM probes is down to about 10 nm, which exceeds the bit length of a magnetic recording with a density of Tbit inch −2 .

Self-assembled FePt nanoparticles hold promise for future ultrahigh-density magnetic recording media because of their high anisotropy and capability to be formed into small and uniform grains. By using a special spin coater, we were able to form a dense array of FePt particles across the entire surface of a 2.5 in. disk substrate. Our method can control the number of layers of FePt nanoparticles. The media deposited with FePt nanoparticles by the spin coater was annealed in a vacuum. We measured read–write properties of the FePt nanoparticle media on a spin stand, and succeeded in detecting a signal of 290 kfci.