Keita Ihara

Microstructures and Magnetic Properties of Fe-(Ta,Nb,Zr)-N Alloy Films

The microstructures and magnetic properties of Fe-(Ta, Nb, Zr)-N alloy films near the eutectic composition were studied. These new soft magnetic alloy films were prepared by N2 reactive sputtering. The structures and magnetic properties were changed by annealing or by adjusting the ratio of the N2 partial pressure to the total gas pressure. Film structures were investigated by X-ray diffraction and TEM, and the following results were obtained, (i) As-prepared films consisted of an amorphous-like phase; (ii) annealed films were a homogeneous mixture of finegrained ¿-Fe and (Ta, Nb, Zr) nitrides; (iii) films annealed at higher temperatures consisted of larger grains of both ¿-Fe grains and (Ta, Nb, Zr) nitrides. Among these, the films (ii) exhibit good soft magnetic properties, small magnetostriction and a saturation magnetization as high as 1.6 T. The soft magnetic properties of Fe-Ta-Zr-N alloy films also had better thermal stability.

Multilayered films of nitride alloys as magnetic head materials

Abstract Multilayered alloy films composed of non-nitride and nitride layers were prepared by N 2 reactive sputtering. Soft magnetic properties were obtained for the films comprising metal-metal elements such as Co-Nb-Zr/Co-Nb-Zr-N when the layer thickness is less than 30 nm and for the films comprising metal-metalloid elements such as Fe-Nb-B/Fe-Nb-B-N when it is less than 60nm. The films showed high 4π M s (12–17kG) and a high permeability (2000–4000 at 1 MHz) after magnetic field annealing at 400–700°C. Magnetic VCR heads manufactured with Co-based multilayered films showed extremely high efficiency both in recording and reproducing characteristics.

Mössbauer studies of compositionally modulated Fe-based nitride alloy films

Abstract We have prepared compositionally modulated FeNbB/FeNbBN films by reactive sputtering with individual layer thicknesses of 100 A. Two types of samples were made, one 6 μm thick and the other 1.5 μm thick on a pure aluminium foil and glass substrate, respectively. We carried out Mossbauer studies in the as-deposited state and after an annealing treatment at 500°C for 1 h in vacuum. The spectrum of the as-deposited sample was typical of an amorphous state with an average hyperfine field (HF) of 26.5 T. In the annealed samples two types of Fe populations in the ratio 33/60 were found. This result is in qualitative agreement with the conclusions of transmission electron microscopy studies.

Magnetic properties of Fe based compositionally modulated nitride alloy films

In the Co-metal based compositionally modulated nitride alloy films, we have noted the fact that the affinity in regards to nitrogen differs among metal elements such as Co and Nb. We have examined systems which contain the metallic elements (Nb) and metalloid elements (B) which have a strong affinity towards nitrogen as Fe-based compositionally modulated nitride alloy films. Based on this, the compositionally modulated nitride alloy films in the Fe-Nb alloys and the Fe-Nb-Si-B alloys show high saturation magnetization and good soft magnetic properties after high temperature annealing. Thus, their suitability as soft magnetic alloy films for use with magnetic heads has become clear. Herein, we report on Fe-based compositionally modulated nitride alloy films. Using the reactive sputtering method, Fe-based compositionally modulated nitride alloy film (CMNF) was formed.