• Korean Journal of Materials Research
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• v.34 no.10
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• pp.506-514
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• 2024

High-frequency soft magnetic Ni, Fe, and Co-based thin films have been developed, typically as nanocrystals and amorphous alloys. These Ni, Fe, and Co-based thin films exhibit remarkably good frequency dependence up to high frequencies of several tens of MHz. These properties arise from the moderate magnetic anisotropy and fairly high electrical resistivity that result from the microstructural characteristics of the nanocrystalline and amorphous states. In this paper, Al-Co/AlN-Co and Al-N/AlN-Co multilayer films were deposited using two-facing-target type sputtering (TFTS). Their microstructures, magnetic and electrical properties were studied with the expectation that inserting Al-Co or Al-N as an interlayer could effectively reduce the coercive force and produce films with relatively high resistivity. A new approach is presented for the fabrication of Al-Co (Al-N)/AlN-Co multilayer films, prepared with the TFTS system. The deposited films were isothermally annealed at different temperatures and investigated for microstructure, magnetic properties and resistivity. The TFTS method used in this experiment is suitable for fabricating Al-Co(Al-N)/AlN-Co multilayer films with different layer thickness ratio (LTR). The annealing conditions, thickness of the multilayer film, and LTR can control the physical properties as well as the microstructure of the manufactured film. Magnetization and resistance increased and coercivity decreased as LTR decreased. The thin film with LTR = 0.175 exhibited high resistivity values of 2,500 µΩ-cm, magnetization of 360 emu/cm³, and coercivity of 5 Oe. Results suggests that thin films with such good resistivity and magnetization would be useful as high-density recording materials.

• Journal of the Korean Society for Heat Treatment
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• v.18 no.5
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• pp.281-287
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• 2005

Titanium aluminium nitride((TiAl)N) film is anticipated as an advanced coating film with wear resistance used for drills, bites etc. and with corrosion resistance at a high temperature. In this study, (TiAl)N thin films were deposited both at room temperature and at elevated substrate temperatures of 573 to 773 K by using a two-facing-targets type DC sputtering system in a mixture Ar and $N_2$ gases. Atomic compositions of the binary Ti-Al alloy target is Al-rich (25Ti-75Al (atm%)). Process parameters such as precursor volume %, substrate temperature and Ar/$N_2$ gas ratio were optimized. The crystallization processes and phase transformations of (TiAl)N thin films were investigated by X-ray diffraction, field-emission scanning electron microscopy. The microhardness of (TiAl)N thin films were measured by a dynamic hardness tester. The films obtained with Ar/$N_2$ gas ratio of 1:3 and at 673 K substrate temperature showed the highest microhardness of $H_v$ 810. The crystallized and phase transformations of (TiAl)N thin films were $Ti_2AlN+AlN{\rightarrow}TiN+AlN$ for Ar/$N_2$ gas ratio of 1:3, $Ti_2AlN+AlN{\rightarrow}TiN+AlN{\rightarrow}Ti_2AlN+TiN+AlN$ for Ar/$N_2$ gas ratio of 1:1 and $TiN+AlN{\rightarrow}Ti_2AlN+TiN+AlN{\rightarrow}Ti_2AlN+AlN{\rightarrow}Ti_2AlN+TiN+AlN$ for Ar/$N_2$ gas ratio of 3:1. The above results are discussed in terms of crystallized phases and microhardness.

• Journal of the Korean Society for Heat Treatment
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• v.21 no.1
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• pp.3-9
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• 2008

Al-Co-N thin films, Al-Co-N/Al-N and Al-Co-N/Al-Co multilayers containing various amounts of Co content were deposited by using a two-facing targets type dc sputtering (TFTS) system. The films were also annealed successively and isothermally at different annealing temperatures. Irrespective of Co content and preparation methods, all the as-deposited films were observed non-magnetized. It was found that annealing conditions can control the magnetic and electrical properties as well as the microstructure of the films.

• Korean Journal of Metals and Materials
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• v.50 no.3
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• pp.248-255
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• 2012

AlN thin films containing various amounts of Co, AlN-Co, and Al-Co alloy particles were prepared using a two-facing-target type dc reactive sputtering (TFTS) system. The as-deposited films exhibited the variable nature expected from an AlN-rich phase, and an amorphous-like phase, depending on the Co content in the films. Specific favorable microstructures were prepared by optimizing annealing conditions. Those microstructures and their magnetic properties and resistivity were investigated. As-deposited films showed very small saturation magnetization and an amorphous-like structure. However, when annealed, the as-deposited amorphous-like phase decomposes into phases of AlN, Co and Al-Co. These annealing induced changes in the microstructure improve the magnetization and resistivity of the films. Further improvement of soft magnetic properties could lead to the material being used for high density magnetic recording head material.

• Korean Journal of Metals and Materials
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• v.49 no.3
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• pp.256-263
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• 2011

We have synthesized Al-Co/AlN-Co multilayer films with different layer thicknesses by using a Two-Facing Target Type dc Sputtering (TFTS) system. The deposited films were annealed isothermally at different temperatures and their microstructure, magnetic properties and resistivity were investigated. The magnetization of the as-deposited films was found to be very small, irrespective of layer thickness. It was found that the annealing conditions and layer thickness ratio of Al-Co to AlN-Co (LTR) were able to control the microstructure, as well as the physical properties of the prepared films. The resistivity and magnetization increased and the coercivity decreased with a decreasing LTR. A high resistivity of 2500 ${\mu}{\Omega}-cm$, a magnetization of 360 $emu/cm^3$, and a coercivity of 5 Oe were obtained for the films with LTR=0.175.

• Journal of the Korean Society for Heat Treatment
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• v.24 no.1
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• pp.16-22
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• 2011

Al-Co/AlN-Co multilayer films with different layer thicknesses were prepared by using a two-facing target type D.C sputtering (TFTS) system. The deposited films were annealed isothermally at different temperatures and their microstructure, magnetic properties and resistivity were investigated. The magnetization of as-deposited films is very small irrespective of layer thickness. It was found that annealing conditions and layer thickness ratio (LTR) of Al-Co to AlN-Co can control the microstructure as well as the physical properties of the prepared films. The resistivity and magnetization increase and the coercivity decreases with decreasing LTR. High resistivity and sufficient magnetization were obtained for the films with LTR = 0.35. Films having such considerable magnetization and resistivity will be a potential candidate to be used for a high density recording material.