Masahiko Naoe

Preparation of Co ferrite thin films with large perpendicular and in-plane coercivities by facing targets sputtering

Thin films with cobalt ferrite layer on ZnO underlayer were prepared at substrate temperature T/sub s/ in the range of 80 approximately 600 degrees C by a facing targets sputtering apparatus. Crystallites in specimen films revealed almost perfect orientation of

Magnetic and structural characteristics of Fe/Al multilayers deposited by ion beam sputtering with Kr

Fe/Al multilayers have been prepared by the ion beam sputtering method with use of Ar and Kr as the working gas. Sputtering by Kr ion beam deposited the multilayer with better crystallinity, smaller interdiffusion between layers, and lower electrical resistivity than sputtering by Ar ion beam. Multilayers with thicknesses of Fe and Al layers of 50–120 A and 15–20 A, respectively, possessed excellent soft magnetism. Such soft magnetism seems to be related, in part, to the fine granulation in Fe layers.

High coercivity of barium ferrite (BaM) films deposited by arc discharge evaporation

In this study, magnetoplumbite barium ferrite (BaM) films were prepared by arc-discharge evaporation and subsequent annealing in air. The films deposited at a substrate temperature T/sub s/ of 150 degrees C and then annealed at T/sub A/ of 800 degrees C in air have exhibited a saturation magnetization M/sub s/ of 380 emu/cc and a coercivity H/sub c/ of 2.2 kOe, almost the same as those of BaM films deposited at T/sub s/ of 500 degrees C. Therefore, the preparation process of depositing BaM films at T/sub s/ of 150 degrees C by arc evaporation and subsequently annealing them at T/sub A/ of 800 degrees C may be applicable for mass production of rigid magnetic disks with high density. >

Effective suppression of internal stresses in Co-Cr films using a mixture of Ar and Kr as the sputtering gas

A lower sputtering gas pressure during the sputtering process tends to result in the deposition of denser Co-Cr films, but also increases compressive internal stresses when a mixture of Ar and Kr is used as the sputtering gas. The internal stresses have been reduced with an increase in the ratio of Kr in the gas mixture.

Thin film tape media with multilayers by sputtering

Magnetic tape with Co-Cr/Ni-Fe multilayers is prepared by using a facing targets sputtering system and 10- mu m thick polymide sheet as a substrate. Read/write characteristics of this tape are investigated using a conventional video tape recorder equipped with a highly sensitive single-pole head. It is proven that even tape with a total thickness of magnetic layers of 0.33 mu m should be highly efficient in recording and reproducing performance. >

Co-Cr/Al multilayers for perpendicular magnetic/magneto-optical two-way recording media

Co-Cr/Al multilayers exhibit excellent magneto-optical characteristics due to the well-defined interfaces between Co-Cr and Al layers. Consequently, these multilayers may be useful in media for perpendicular magnetic/magneto-optical two-way magnetic recording systems.

High permeability of Fe–Al–Si alloys films deposited on plasma‐free substrate by dc bias sputtering

Soft magnetic Fe75Al10Si15 (Sendust) films were deposited on substrates separated from the high‐energy plasma using the facing targets sputtering (FTS) apparatus. The Ar bias voltage VB was changed in the range of 0 to −150 V, and the substrate temperature Ts was adjusted in the range of 50∼400u2009°C. Films deposited at PAr of 1.0 mTorr and VB of −100 V possessed almost the same composition as that of the targets: Fe75Al10Si15. Films deposited at PAr=1.0 mTorr, VB=0 V and Ts=350u2009°C exhibited a saturation magnetization 4πMs=11.7 kG, a coercivity Hc=0.6 Oe, and a static relative permeability μrs=5000. On the other hand, films deposited at PAr=1.0 mTorr, VB=−100 V and Ts=50u2009°C exhibited 4πMS=12.0 kG, HC=0.4 Oe and μrs=8000. In addition, these films exhibited radio frequency relative permeability μrf of 2850 and 1050 at fM=10 and 50 MHz, respectively.

Magneto-optical characteristics of BaM ferrite/Co-oxide multilayered films

Multilayers composed of 25 bilayers of magnetoplumbite type of barium ferrite (BaM) layers as thin as 120 AA and CoO or Co/sub 3/O/sub 4/ layers on ZnO/SiO/sub 2//Si substrates were prepared by vacuum-arc evaporation, X-ray diffraction indicated these multilayers possessed clear periodic structure with sharp and flat interfaces. Mossbauer spectroscopy indicated strong magnetic interactions among the iron and cobalt ions through the interfaces. The apparent orientation of magnetic spins in the BaM/CoO multilayer was parallel to the layer planes. Multilayers exhibited a magnetic spin orientation which was oblique to the layer planes, a coercivity H/sub c/ of 2.0 kOe and Kerr rotation angle theta /sub k/ of 10 min. >

Improvement in soft magnetism of Sendust sputtered films for high performance MIG head

Abstract Sendust thin films with relative permeability μ r up to 6000 were prepared by using the facing targets sputtering (FTS) system which is one of the plasma-free sputtering methods. The optimum values of the argon gas pressure P Ar , the substrate temperature T s and the bias voltage to the substrate V b were found.