• Proceedings of the Korean Magnestics Society Conference
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• 2007.05a
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• pp.162-162
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• 2007

• Proceedings of the Korean Magnestics Society Conference
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• 2000.09a
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• pp.500-501
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• 2000

• Proceedings of the Korean Magnestics Society Conference
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• 2002.04a
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• pp.136-137
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• 2002

No Abstract, See Full Text

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.5
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• pp.478-483
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• 2005

In this paper, we synthesized 10 to 20 nm diameter NiFe nanoparticles and nanoparticle films utilizing supersonic jet deposition of nanoparticle aerosols generated by laser ablation of $30\;to\;45{\mu}m$ diameter permalloy $(Ni_{81}Fe_{19} \;at\;{\%})$ microparticles. The component and composition of the nanoparticles were characterized by an energy dispersive X-ray spectroscopy. The morphology of the nanoparticles and nanoparticle films was analyzed by a high-resolution transmission electron microscopy and a scanning electron microscopy, respectively. The experimental results showed that the nanoparticles and nanoparticle films have remarkable properties with an excellent preservation of the composition of feedstock permalloy microparticles. The purpose of the present work is to present details on the composition and nanostructural characterizations for NiFe nanoparticles and nanoparticle films prepared by laser ablation of microparticles (LAM).

• Journal of the Korean Magnetics Society
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• v.14 no.5
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• pp.163-168
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• 2004

We prepared ultra thin film structure of Si(100)/ $SiO_2$(200 nm)/Ta(5 nm)/Ni$_{80}$Fe$_{20/(l～15 nm)}$Ta(5 nm) using an inductively coupled plasma(ICP) helicon sputter. Magnetic properties and cross-sectional microstructures were investigated with a superconduction quantum interference device(SQUID) and a transmission electron microscope(TEM), respectively. We report that NiFe films of sub-3 nm thickness show the B$_{bulk}$ = 0 and B$_{surf}$=-3 ${\times}$ 10$^{-7}$(J/$m^2$). Moreover, Curie temperature may be lowered by decreasing thickness. Coercivity become larger as temperature decreased with 0.5 nm - thick Ta/NiFe interface intermixing. Our result implies that effective magnetic properties of magnetoelastic anisotropy, saturation magnetization, and coercivity may change abruptly in nano-thick films. Thus we should consider those abrupt changes in designing nano-devices such as MRAM applications.

• Journal of the Korean Ceramic Society
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• v.29 no.5
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• pp.383-390
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• 1992

We investigated the effect of substrate on the properties of the Ni-Zn-Cu ferrite thin films deposited on SiO2 (1000∼3000${\AA}$) / Si (100) substrate at various conditions by rf magnetron sputtering. A disktype Ni-Zn-Cu ferrite sintered by conventional ceramic process and argon gas were used as a target and a sputtering gas, repectively. The compositions of the thin films measured by EPMA were similar to target composition (Fe: 65.8 at%, Ni: 12.7 at%, Cu: 6.7 at%, Zn: 14.8 at%) irrespective of substrate temperature. Amorphous thin films were deposited when substrate was not intentionally heated, but the films came to crystallize with increasing substrate temperature, and crystalline thin films were deposited at substrate temperature above 200$^{\circ}C$. Below 250$^{\circ}C$ saturation magnetization (Ms), remanence (Mr) and coercivity (Hc) of the ferrite thin film increased with the substrate temperature due to the increase of grain size and the improvement of crystallinity. And above 250$^{\circ}C$, Ms, Mr increased slightly, but Hc of the amorphous thin films increased due to crystallization, whereas that of the crystalline thin films decreased because of grain growth and stress release.

• Journal of the Korean institute of surface engineering
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• v.26 no.2
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• pp.45-54
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• 1993

In this study, magnetic properties of anodized Al film deposited with ferro-magnetic metals in the capacity of perpendicular magnetic recording media were measured and evaluated to find out the role of structure and morphology of the oxide films on magnetic characteristics. The object of this work was to present the conditions of magnetic thin film formation with more superior magnetic property. Anodizing was carried out under various conditions, and then the anodized film were electro-deposited with Co, Ni, Fe and their alloys. Coercive force and residual magnetization in perpendicular direction increased as the pore length of anodized film increased. It was attributed to the increase of the amount of depoisted metals and the ratio of length/diameter of pores. Morphology of anodized films in phosperic acid was not similar to that of sulfuric acid, and thin films in the former solution had perpendcular magnetic anisostropy because of large diameter, irregular length and distribution of the pores. It was found that magnetic properties of the thin films, which had doubled layer of two metals, were dominated by the metal electrodeposited on the surface of the anodized oxide films.

• Journal of the Korean Magnetics Society
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• v.16 no.5
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• pp.249-254
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• 2006

CoFeNi alloys are some of the most studied soft magnetic materials because of their superial properties over FeNi alloys as write head core materials in HDD and MEMS. We studied the effect of magnetic property according to size and orientation of crystal for electroplated Co-Fe-Ni alleys. In case of heat treated ternary alloy, it affect the change of crystal size and structure. In this study, it intends to improve the magnetic properties of CoFeNi thin film by heat treatment. Minimized coercivity and increased magnetization are due to heat treatment from $300^{\circ}C\;to\;400^{\circ}C$. As a bcc phase formation, it grow to amount of magnetization.

• Journal of Magnetics
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• v.5 no.3
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• pp.90-98
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• 2000

The change in the magnetic properties of a spin-valve multilayer with the structure IrMn (9 m)/CoFe (4 nm)/Cu (2.6 nm)/CoFe (2 nm)/NiEe (6 nm) is investigated as a function of the size and the aspect ratio. At a fixed aspect ratio (the length/width ratio) of 2, the magnetostatic interactions begin to affect the magnetic properties substantially at a spin-valve length of 5 $\mum$, and, at a length of 1 $\mum$, they become even more dominant. In the case of a fixed multilayer size (2.4 $\mum$) which is indicated by the sum of the length and the width, magnetization change occurs by continuous spin-reversal and M-H loops are characterized by no or very small hysteresis at aspect ratios smaller than unity, At aspect ratios greater than unity, magnetization change occurs by spin-flip resulting in squared hysteresis loops. A very large changes in the coercivity and the bias field is observed, and these results are explained by two separate contributions to the total magnetostatic interactions: the coercivity by the self-demagnetizing field and the bias field by the interlayer magnetostatic interaction field.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.19 no.6
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• pp.282-287
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• 2009

$Ni_xFe_{100-x}$ films with a thickness of about 100nm were deposited on Si(100) substrates at room temperature by a DC magnetron co-sputtering using Fe and Ni targets. Compositional, structural, electrical and magnetic properties of the films were investigated. $Ni_{67}Fe_{33}$, $Ni_{55}Fe_{45}$, $Ni_{50}Fe_{50}$, $Ni_{45}Fe_{55}$, $Ni_{40}Fe_{60}$ films are obtained by increasing the sputtering power of the Fe target. The films of x < 55 have BCC structure and show the phase transformation after annealing at the range of $300{\sim}450^{\circ}C$ for 2 h. On the other hand, the films of x < 50 have the mixed crystalline phases of BCC and FCC after the annealing treatment. The saturation magnetization was decreased initially by the phase transformation effect but then increased again after annealing at $450^{\circ}C$ due to the grain growth and crystallization of BCC phases.