Nanostructured FePt:B[sub 2]O[sub 3] thin films with perpendicular magnetic anisotropy.

FePt/B[sub 2]O[sub 3] multilayers were deposited by magnetron sputtering onto 7059 glass substrates. By annealing the as-deposited films at 550 °C, nanostructured FePt:B[sub 2]O[sub 3] films consisting of FePt grains with L1[sub 0] structure, embedded in a glassy B[sub 2]O[sub 3] matrix, were obtained. The c axes of the FePt grains can be made to align with the film normal direction, which results in a perpendicular anisotropy constant of 3.5x10[sup 7] erg/cc. The films remain layered structures after annealing when the B[sub 2]O[sub 3] layer thickness exceeds 16 Å. The nanostructure of the films was investigated by transmission electron microscopy. The coercivities and the average grain sizes of the films are dependent on the B[sub 2]O[sub 3] concentrations, with coercivities varying from 4 to 12 kOe, while average grain sizes vary from 4 to 17 nm. Strong perpendicular anisotropy, adjustable coercivity, and fine grain size suggest this nanocomposite system might have significant potential as recording media at extremely high areal density. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]