Magnetic properties of nanometer-size CoPt particles

Abstract

We have prepared nanometer-size, isolated CoPt particles. The particles in the range of 100-300 nm in diameter were formed by annealing thin films in the temperature range of 550-800°C. Films with magnetic coercivity as high as 30 kOe were achieved. The results indicate that the high magnetic coercivity was obtained because the crystallite size approaches that of noninteracting single-domain particles.

Nanocomposite CoPt:C films for extremely high-density recording

“…͑3͒ can be well satisfied even with dϭ4 nm (V ϭ6.4ϫ10 Ϫ20 cm 3 ). Large H c , which originate from the high K u value, were reported in CoPt bulk samples, 9 CoPt films, 10 CoPt nanoparticulates grown on quartz substrates, 11 and CoPt/Ag films. 12 For the purpose of forming small CoPt grains with weak exchange coupling, C would be an ideal isolation material between neighboring CoPt grains because there exist neither stable Co nor Pt carbides.…”

“…All as-deposited films are magnetically soft with H c less than 100 Oe. They most likely consist of disordered fcc CoPt, [9][10][11][12] which is the high-temperature phase, and/or amorphous CoPt in addition to C matrix. Since fct CoPt is the low-temperature phase, appropriate annealing leads to the transition from the fcc CoPt phase to the fct CoPt phase in CoPt:C films.…”

Preparation and Characterization of Electrodeposited Fe-Pd Binary Alloy Film

“…1) Example of recent interest are CoPt, 2) Fe-Pt 3) and Fe-Pd, 4) where strong interdependencies between magnetic and degree of long range chemical ordering have been observed. Therefore, Fe-Pd alloys, both in bulk and in thin film, have been the subjects of investigation by a number of researchers.…”

Orientation-controlled nonepitaxial L1 CoPt and FePt films

“…Once the material between grains is depleted, high diffusion barriers prohibit further grain growth and coalescence. Liou et al 16 found that longtime annealed 10 nm CoPt films form well-separated nanoparticles. The ͑001͒ and ͑100͒ textures of the nuclei can thus be preserved for thinner films even after long annealing times.…”