Ba–ferrite thin-film disk for perpendicular magnetic recording

Abstract

The authors have prepared Ba–ferrite film disks and evaluated their magnetic read/write characteristics. The c-axis-oriented Ba–ferrite thin films were formed epitaxially on c-axis-oriented ZnO films by means of a targets-facing-type sputtering system. The direction of easy magnetization in the film with perpendicular crystalline anisotropy is almost perpendicular to the film plane. Thus, the perpendicular remanence is more than 60 times as large as the in-plane one. The simple Ba–ferrite films, however, have a coercive force, Hc⊥ above 2 kOe which is too large to write on by means of a conventional head. The substitution of In3+ in the Ba–ferrite films makes the Hc⊥ values decrease to about 1 kOe without increasing the critical temperature, Tcritical, of c-axis orientation. The read/write characteristics of the films were measured with a MnZn–ferrite ring head. The reproduced signal exhibits clear dipulsive waveforms as the dipulse ratio exceeds 0.7. Furthermore, the overwrite ratio decreases below −28 dB for the In3+-substituted Ba-ferrite film disk. The Ba–ferrite film disks have promising potential as a high-density perpendicular magnetic recording medium.

The effect of deposition and annealing conditions on textured growth of sputter-deposited strontium ferrite films on different substrates

“…M -type barium ferrite ͑BaM͒ films with c-axis oriented normal to the film plane have been reported by different workers. [1][2][3][4][5][6][7][8][9] These films have been deposited using different deposition techniques such as dc and rf diode sputtering, targets facing type sputtering, laser ablation, etc. 4 -7 These films have been crystallized either by in situ heating of substrates or postdeposition annealing of the films.…”

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] M -type ferrites have a large uniaxial magnetocrystalline anisotropy and generally the hexagonal c axis is the easy axis of magnetization. Hence, there has been interest in depositing these films having c-axis orientation.…”

Thick barium ferrite films use for passive isolators

“…In particular, M-type hexagonal ferrites (BaFe 12 O 19 or BaM) have been extensively studied due to their potential applications in recording and millimeter-wave devices [2][3][4]. The main interest has been to deposit these films with c-axis oriented either normal to the film plane or in the film plane [5,6].…”

Magneto-Optical Properties of the Epitaxial Barium Hexaferrite Films Prepared by Pulsed Laser Deposition

“…In order to get the films with the high c-axis orientation and the smooth surface, the deposition at various substrate temperatures (Ts) and oxygen atmosphere pressure (P0 2 ) were carried out. The Fe/Ba ratio of the films was nearly equal to that of the target, and independent of P0 2 and Ts.…”

“…Hexaferrite films such as BaFe 12 0 19 , BaFe 1s 0 2 7 and so on are promising candidates for both high density recording media and microwave /millimeter wave devices [1,2]. Up to now, these films were mainly prepared by a sputtering method and their studies were directed to the magnetization and crystal characterization.…”