Amorphous TbFe Films Research Articles

Aging phenomena in TbFe thin films

The aging phenomenon of amorphous TbFe thin films when protected with a SiO2 layer is studied by plotting the hysteresis cycles of the films at various time intervals. The changes observed in the coercive field are related to the changes in the Tb content of the layer. It is suggested that Tb atoms, in spite of their size, can move easily in the layer and tend to migrate out of the amorphous TbFe film. This hypothesis is confirmed by the differences observed in TbFe films deposited on pure Tb underlayers of different thicknesses and by Auger profiles carried out on aged samples.

熱磁気記録したＴｂ‐Ｆｅ膜の透過電子顕微鏡観察

Amorphous Tb-Fe films were prepared on thin carbon film and glass substrates by RF sputtering method. The films were irradiated with pulsed Ar laser beam, the energy range of which was that commonly adopted for thermo-magnetic recording. Thermal effects were studied mainly by transmission electron microscopy. The thermally influenced area depended largely on the film thickness over the range from 200 to 2000 Å. he structure of the irradiated areas changed from amorphous to crystalline, while magnetization of the corresponding areas turned from perpendicular to in-plane orientation. In a 500 Å Tb30Fe70 film on a carbon film substrate a circular area of 2.5 μm in diameter was crystallized by one 4 mW pulse of 1 μs. The damage was more evident in thinner films.

Substrate bias voltage dependences of magnetic properties in amorphous Tb-Fe films

Substrate bias voltage dependences of magnetic properties were measured in amorphous Tb-Fe films. The bias voltage dependence of K u shows a minimum around V b = -60V. This is explained by effects of the preferential resputtering and oxidation of Tb atoms during deposition.

Static and dynamic properties of thermonagnetic writing in amorphous TbFe films

The domain structure in the bit written thermomagnetically is investigated in detail, and also the dynamic process of the flux reversal in the writing is studied experimentally and theoretically. The formation of the domain structure in a written bit is explained consistently.

The microstructure and magnetic properties of amorphous TbFe(O 2) thin films

Amorphous Tb-Fe films were prepared by vapour deposition in ultrahigh vacuum or at partial oxygen pressures in the range 10 −7–10 −3 Pa. In the highly oxygen-doped films we observed the presence of both iron-rich crystallites and terbium oxide. Interpretation of the magnetic domain structure indicates a gradual change in the easy axis of magnetization from perpendicular to in-plane as the oxygen content in the films increases. At the highest oxygen partial pressures we found both a rapid increase of the saturation magnetization and a drop in the Curie temperature and coercive force. The correlation of structural features and magnetic properties is discussed.

Thermomagnetic contact printing in amorphous Tb-Fe films

Ferrimagnetic amorphous Tb-Fe films prepared by rf sputtering or thermal evaporation have a perpendicular anisotropy, a low Curie point (Tc) and large values of coercivity (Hc) over a wide range of temperature. This paper describes the effect of thermal annealing and the contact printing method by Curie point writing for visual display of magnetic information recorded on magnetic tapes or discs. The values of Hc, Tc and the room temperature magnetization (Ms) are reduced by thermal annealing. Thermomagnetic contact printing in an amorphous Tb-Fe film has been tried. It is accomplished by putting the film on the recorded magnetic tape or disc and then heating up the film by photoflash light. The information is observed by means of the polar Kerr effect. In this printing method high resolution printing is realized and analog printing is possible.

Thermomagnetic writing in Tb-Fe films

Thermomagnetic writing in amorphous Tb-Fe films prepared by thermal evaporation or rf-sputtering is described. These films have a low Curie temperature (75°C) and large values of coercive force over the wide range of temperature. Spots are thermomagnetically written and erased by using a He-Ne laser in conjunction with external magnetic field, and 1 ∼ 2 micron spots are written stably with low laser power. At this writing, a new property was found, that is, the Kerr contrast of the spots gradually varies with a value of the external magnetic field. Temperature dependences of coercive force and magnetization, spot diameter as a function of writing laser power and the Kerr contrast of spots as a function of external magnetic field are reported.

Magnetic properties of amorphous Tb-Fe thin films prepared by rf sputtering

The magnetic properties of amorphous TbxFe1−x films prepared by rf cosputtering were studied. For 0.15<x<0.28, the films have uniaxial magnetic anisotropy normal to the film plane sufficient to stabilize cylindrical domains. The Curie temperature Tc and the coercivity Hc were measured as a function of composition. Tc increases monotonically with increasing Tb content in the alloy films in the region 0.1 < x<0.5. Hc is about one order of magnitude large, in contrast with amorphous Gd-Fe films at room temperature, and it increases further at low temperatures. Amorphous Tb-Fe films have a high potential for thermomagnetic recording using the Curie temperature because of the large Hc (1–5 kOe) and the low Curie temperature (∼120°C).