No abstract

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.

Fine tuning of the sizes of FePt nanoparticles has been realized by a simple modification of a solution phase synthesis, which consists of the decomposition of Fe(CO)5 and the reduction of Pt(acac)2. The key method used to control the particle size is the use of surfactants, and only a change in their amount is required to vary the average sizes of the FePt nanoparticles from 2 to above 4 nm. The resultant nanoparticle volume is proportional to the surfactant amount; this makes the synthesis of FePt nanoparticles of desired sizes possible.

No abstract

This letter reports the results obtained by measuring the temperature dependence of the coercivity of magnetically isolated L10-FePt nanoparticles in agglomeration-free films deposited by using a dispersion stabilizer and a spin-coat technique. These measurements not only give the basic magnetic parameters of the nanoparticles but also provide information about the nanoparticle ordering process. The temperature at which isolated FePt nanoparticles start to order seems to be about 650°C.