CoZr Amorphous Films Research Articles

Laminated CoZr amorphous thin-film recording heads

Recording heads with four-layer laminated CoZr/Ta films as pole pieces have been fabricated using rf sputter deposition and ion milling techniques. Typical 4πMs of 14 000 G were obtained for CoZr amorphous films compared with 10 000 G for Permalloy films. Recording tests performed with this laminated CoZr/Ta film head indicate 8–12 dB better overwrite than with plated Permalloy film heads having an identical structure. However, the former exhibits a 10%–25% lower amplitude than the latter. This may be attributed to the thermal degradation of the initial permeability μi of the CoZr film during head-fabrication processes. This CoZr/Ta head also shows poorer amplitude stability than the plated Permalloy head.

Induced Magnetic Anisotropy of CoTi and CoZr Amorphous Films

The relaxation process of induced magnetic anisotropy of CoTi and CoZr films is discussed and their permeability compared with that suggested by the single domain theory. The anisotropy energy of the samples was evaluated using the hard and easy axes magnetization curves, and the permeability was measured at 1.4 MHz with the Q meter method. The activation energy of the anisotropy relaxation process in these films was higher than that in CoFeB films, indicating greater thermal stability. The experimental value of the permeability of CoTi films substantially agreed with the predicted values of the single domain theory. A similar results was obtained in CoZr films.

Magnetic properties of CoZr amorphous films prepared by low energy ion beam sputtering

In this paper, magnetic properties of CoZr amorphous films prepared using low-energy ion-beam sputtering are investigated by varying the accelerator voltage and beam current of a single-grid ion-beam sputtering system. It is shown that CoZr films become amorphous with a lower Zr content when the films are prepared with lower accelerator voltage or lower ion-beam current. It is also clarified that the saturation magnetostriction constant of amorphous CoZr film becomes smaller as the Zr content becomes smaller ; a film with a Zr content of approximately 3.3at% has a magnetostriction constant of zero without adding a third element such as Nb, Ta or Re. CoZr amorphous films with a saturation magnetization of more than 1.5T, a coercive force of less than 0.2Oe and a magnetostriction constant of zero could be obtained using low-energy ion-beam sputtering with an accelerator voltage of less than 300V.

Differences between Sputtering Methods in The Formation of Amorphous Magnetic Alloy Films

ABSTRACTFe-Si, Co-Ta and Co-Zr amorphous films have been deposited by using various sputtering methods (conventional rf diode sputtering, rf triode sputtering, dc Targets Facing type sputtering (dc TF sputtering) and dual ion beam sputtering (DIB sputtering)). The lower limit of the Si and Ta content to form amorphous Fe-Si and Co-Ta films changes significantly with the sputtering method. These differences between the sputtering methods are mainly caused by the differences in the plasma potential which affects the amount of ion bombardment to the film surface during sputtering,and the minimum content of Si or Ta to obtain amorphous films decreases as the plasma potential increases. These results indicate that the ion bombardment suppresses the growth of crystallites and promotes the formation of the films with amorphous structures. This is confirmed by the deposition of Co-Ta and Co-Zr amorphous films under the condition of various amount of ion bombardment by using a DIB sputtering system.

Effect of Au addition on the magnetic properties of Co-Zr amorphous films

The effect of Au addition on the magnetic properties and thermal stability of amorphous CoyZr1−y alloys produced by sputtering is described. Change of the saturation magnetization, the saturation magnetostriction, and the crystallization temperatures were measured for Au additions up to 2.0 at. %. For y=87.2 little appreciable effect was observed, but for y=93.2 and 94.2 rapid decrease of the magnetostriction was observed for small amounts of Au additions. Thermal stability of magnetic softness is also improved appreciably.

A thin film head for high density magnetic recording using CoZr amorphous films

A thin film head using CoZr amorphous films has been developed for high density magnetic recording. The head has a single-layered 17-turn spiral copper coil, 0.2-μm head gap length, 15-μm track width, and 2-μm-thick CoZr films on an IBM 3370 type slider. The copper coil was electroplated through a photoresist pattern, which was fabricated by the oxygen ion milling to obtain a high aspect ratio (1.5 μm width, 3.4 μm thickness, 3.5 μm space). CoZr films used here have excellent magnetic properties, such as low coercive force (Hc≤0.05 Oe), high permeability ( μ≂3500 at 10 MHz), and high saturation magnetization (4πMs ≂14 000 G). These heads were evaluated using 8-in. Co-Ni-P plated disks which have a 300-Å-thick magnetic layer (Hc=600 Oe, Br =7200 G) and a 200-Å-thick protective layer. D50=36 KFRPI and overwrite=−34 dB (24 KFRPI on 8 KFRPI) were obtained at 19.7 m/sec relative velocity and 0.25 μm head-disk spacing. These values were superior to those for heads using Permalloy films (D50=25 KFRPI, overwrite=−20 dB). It was concluded that CoZr amorphous thin film heads have superior capabilities for high density magnetic recording.