• Journal of the Korean institute of surface engineering
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• v.35 no.2
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• pp.107-112
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• 2002

We have studied diffusion behavior of NiFe/Ag bilayer deposited by on silicon Ion Beam Sputtering methods. The diffusion behavior of NiFe and Ag in NiFe/Ag thin film is analyzed by Medium Energy Ion Scattering Spectroscopy. For samples without Ta underlayer, silicides such as Ni-Si or Fe-Si were formed at Si substrate and NiFe interface. In contrast, Ag predominantly diffused into the NiFe layer probably through their grain boundaries for Ta underlayered samples.

• Proceedings of the Korean Magnestics Society Conference
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• 1997.05a
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• pp.24-25
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• 1997

• Proceedings of the Korean Magnestics Society Conference
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• 1997.11a
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• pp.22-23
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• 1997

• Journal of the Korean Magnetics Society
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• v.9 no.1
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• pp.41-47
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• 1999

$Buffer/[NiFe/Cu/CoFe(Co)/Cu]_N$ spin valve multilayers prepared by dc magnetron sputtering on a corning glass substrate using NiFe and CoFe(Co) posses different coercivities. Dependence of magnetoresistance on the type and thickness of buffer layer, thickness of Cu, NiFe, stacking number of multilayer, substrate temperature and annealing temperature in the form $[NiFe/Cu/CoFe(Co)/Cu]_N$ spin-valve multilayers were investigated. To evaluate effect of magnetoresistance for this samples, X-ray diffraction analysis, vibrating sample magnetometer analysis, and magnetoresistance measurement (4-probe method) were performed the maximum magnetoresistance ratio and coercivity were 7.5 % and 140 Oe, respectively for $Cr-50{\AA}/[NiFe-20{\AA}/Cu-{\AA}/Co-20{\AA}/Cu-50{\AA}]_10$ at substrate temperature of 9$0^{\circ}C$. Magnetoresistance slope maintained 0.25%/Oe until 15$0^{\circ}C$ of annealing temperature, and then decreased to 0.03%/Oe at 20$0^{\circ}C$. It was confirmed that the main factor of thermal stability was deteriorating of soft magnetic properties in the NiFe layer.

• Journal of the Korean Magnetics Society
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• v.11 no.3
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• pp.104-108
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• 2001

The effect of specular electron scattering on natural oxidation of free layer in NiO spin valves have been investigated. The magnetoresistance (MR) ratio and the exchange biasing field ( $H_{ex}$) of NiO(600 $\AA$)Ni$_{81}$$Fe_{19}$(50$\AA$)/Co(7 $\AA$)/Cu(20 $\AA$)/Co(7 $\AA$)Ni$_{81}$$Fe_{19}$(70 $\AA$) spin valves were increased from 4.9 % to 7.3 %, and 110 Oe to 170 Oe after natural oxidation in the atmosphere for 80 days, respectively. The sheet resistivity p decreased from 28$\mu$$\Omega$m to 17$\mu$$\Omega$m, but $\Delta$$\rho$ did not almost change after the oxidation. The spin valves enhanced by the specular electron scattering in the natural]y Co/NiFe/NiFe $O_{x}$ free layer were confirmed from the depth profiles using Auger electron spectroscopy.scopy..

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.221-221
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• 2003

본 연구에서는 스핀밸브 다층박막에서 교환 바이어스에 영향을 끼치는 요인 중 하나인 강자성층과 반강자성층사이의 접합 계면에서의 표면 거칠기 [1,2]를 줄이기 위해 현재 반도체 공정에 사용되고 있는 이온빔 에칭 장비를 사용하여 스핀 밸브 다층박막의 씨앗층 에칭에 따른 교환 바이어스를 알아보고자 하였다. 스핀밸브 구조는 강자성층/비자성층/강자성층의 기본구조를 갖는데 이중 하나의 강자성층의 스핀방향이 반강자성층에 의해 고정되는 구조[3]로써 이러한 고정 효과를 교환 바이어스(exchange bias)라 부른다. 교환 바이어스(exchange bias)현상은 강자성과 반강자성의 접합계면에서 강한 상호 교환결합력에 의해 나타나는 현상으로 이러한 교환 바이어스 특성은 하드드라이브의 고밀도 자기헤드소자 및 비휘발성 자기 메모리소자에 응용되어 기존의 자기저항 소자의 특성을 크게 향상시킬 수 있게 되었다.

• Journal of the Korean Magnetics Society
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• v.3 no.4
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• pp.293-297
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• 1993

Exchange coupled $NiFe/TbCo/Sio_{2}$ thin films for magnetoresistive heads were sputter deposited using RF diode sputtering method, and their magnetic characteristics were measured. TbCo films were deposited using a composite target, which is composed of Tb chips epoxied on a Co target. NiFe($400\AA$)/TbCo($1500\AA$)/$SiO_{2}$($500\AA$) films were deposited using a TbCo target having 30 % of Tb area ratio, which showed 25 Oe of the exchange field without substrate bias and 12 Oe with -55 V of substrate bias. The effective in-plane coercivities of the three layer films fabricated with less than -55 V of substrate bias were approximately proportional to the perpendicular coercivities of the TbCo layer only. The films fabricated with a Theo target of 28 % area ratio showed the same trend. However, the exchange field decreased to 4 Oe without the substrate bias and 7 Oe with -55 V of substrate bias. In the films fabricated with 1000 W of power and the target of 36 % area ratio exhibited 100 Oe of exchange field and 3 Oe of coercivity. As the thickness of NiFe layer increased, the exchange field decreased.

• 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 the Korean Magnetics Society
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• v.12 no.4
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• pp.143-148
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• 2002

We report an experimental evidence of coexistence of the strong and weak exchange couplings in unidirectional NiO/NiFe (antiferromagneticlferromagnetic) bilayer thin films. The exchange bias was measured by VSM and AMR techniques and then, analyzed into the strong and weak exchange couplings by means of a regression method. In NiO(60nm)/NiFe(10nm) film, the ratio of the weak exchange coupling field over the average exchange coupling field was found to be almost unchanged within it range from 0.2 to 0.4 irrespective to the strength of an applied field. However, the ratio increased among the samples with decreasing the average exchange coupling field due to the increment of the weak exchange coupling area.

• Journal of Sensor Science and Technology
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• v.1 no.1
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• pp.23-34
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• 1992

In order to fabricate magnetoresistive sensor, Fe-Ni and Co-Ni alleys were evaporated on the slide glass and the silicon wafers. Saturation magnetic induction($B_{s}$), coercive field strength($H_{c}$) and magnetoresistance were measured for fabricated samples. The evaporated Fe-Ni thin films show that the saturation magnetic induction was 0.65 T, and coercive field strength was 0.379 A/cm, and this value was changed to 0.370 A/cm(//), 0.390 A/cm(${\bot}$), respectively after magnetic annealing. For the measurement of coercive field strength, magnetizing frequency of 1 kHz was used. For the fabricated sensor element, the change of magnetoresistance (${\Delta}R/R$) was excessively unstable due to oxidation in the process of fabrication. The evaporated Co-Ni alloy thin films show that saturation magnetic induction was 0.66 T, and coercive field strengthes were 5.895 A/cm(//), 5.898 A/cm(${\bot}$), respectively, after magnetic annelaing. The change of magnetoresistance(${\Delta}R/R$) was $3.6{\sim}3.7%$ of which value was excessively stable to room temperature. Fe-Ni thin film could have many problems due to large affinity in the process of fabrication of magnetoresistance sensor, but Co-Ni thin film could be a suitable material for fabrication of magnetoresistance sensor, because of its small affinity and definite magnetoresistance effects.