Nanostructured FePt : B2O3 thin films with perpendicular magnetic anisotropy

FePt/B2O3 multilayers were deposited by magnetron sputtering onto 7059 glas s substrates. By annealing the as-deposited films at 550 degrees C, nanostr uctured FePt:B2O3 films consisting of FePt grains with L1(0) structure, emb edded in a glassy B2O3 matrix, were obtained. The c axes of the FePt grains can be made to align with the film normal direction, which results in a pe rpendicular anisotropy constant of 3.5x10(7) erg/cc. The films remain layer ed structures after annealing when the B2O3 layer thickness exceeds 16 Angs trom. The nanostructure of the films was investigated by transmission elect ron microscopy. The coercivities and the average grain sizes of the films a re dependent on the B2O3 concentrations, with coercivities varying from 4 t o 12 kOe, while average grain sizes vary from 4 to 17 nm. Strong perpendicu lar anisotropy, adjustable coercivity, and fine grain size suggest this nan ocomposite system might have significant potential as recording media at ex tremely high areal density. (C) 2000 American Institute of Physics. [S0003- 6951(00)01540-0].