• Journal of the Korean Vacuum Society
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• v.4 no.1
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• pp.67-76
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• 1995

자기저항헤드용 Ni-Fe-Co/Cu/Ni-Fe-Co/Fe-Mn 다층박막에서 자기적 성질과 전기적 성질에 관하여 조사하였다. 저 포화자계에서 고 자기저항을 나타내는 스핀 밸브형 다층박막을 제작하기 위하여 Borond이 도핑된 p-type Si(100)기판위에 Ni-Fe-Co 단층박막과 Si/Ni-Fe-Co/Cu/Ni-FeCo, Si/Ni-Fe-Co/Fe-Mn 구조의 다층막을 제작하여 자기적 특성을 조사하였다. Ni-Fe-Co 단층박막의 자기적 특성은 고정된 아르곤 분압에서 박막의 두께 등에 의존성이 있는 것으로 나타났다. 또한 Si/Ni-Fe-Co($70AA$)/Fe-Mn 구조에서 Ni-Fe-Co와 Fe-Mn 계면에서의 두 자성층의 이방성 차이에 의해서 발생되어지는 교환자기이방성이 존재하였으며, 교환자기이방성자계값은 Fe-Mn 두께가 $150\AA$일 때 가장 큰 값을 나타내었다. Ni-Fe-Co texture와 교환자기이방성자계값은 Fe-Mn 두께가 $150\AA$일 때 가장 큰 값을 나타내었다. Ni-Fe-Co texture와 교환자기이방성자계값의 의존성을 알아보기 위하여 Ti, Cu를 바닥층으로 사용하였다. Ti을 바닥층으로 사용하였을 경우, 교환자기이방성자계값은 23.5 Oe 정도의 가장 큰 값을 나타내었다. XRD 분석결과, Ti 바닥층이 Cu 바닥층이나, 바닥층이 없는 경우와 비교하여 성막된 Ni-Fe-Co 자성층의 강한 fcc(111) texture를 형성하는 것으로 나타났다. 각각의 단층박막과 다층박막에서의 자기적 특성을 측정한 후, Si/Ti($50\AA$)/Ni-Fe-Co($70\AA$)/Cu($23\AA$)/Ni-Fe-Co($70\AA$)/Fe-Mn(150$\AA$)/Cu(50$\AA$)의 스핀밸브구조를 갖는 다층박막을 제작하였으며, 11 Oe의 낮은 포화자계값에서 4.1%의 고 자기저항값을 얻을 수 있었다.

• Journal of the Korean Magnetics Society
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• v.20 no.1
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• pp.8-12
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• 2010

The magnetostriction and stress of multilayer $NiFeCr/(Cu/Co_{90}Fe_{10}){\times}N/NiFeCr$ films were investigated. As the number of Cu $15{\AA}$/CoFe $15{\AA}$ bilayers was increased, the saturation magnetostriction decreased from $-5.6\times10^{-6}$ at 2 bilayers to $-8.5\times10^{-6}$ at 20 bilayers. A change of CoFe thickness from 10 to $20{\AA}$ caused a decrease in the magnitude of tensile stress from 980MPa to 590MPa as the number of Cu $15{\AA}$/CoFe $15{\AA}$ bilayers increased from 2 to 20. The maximum magnetostrictive anisotropy field that could be developed due to nonzero magnetostriction and stress is calculated to be 135.7 Oe when the number of Cu $15{\AA}$/CoFe $15{\AA}$ bilayers is 10.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.10 no.1
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• pp.36-41
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• 2000

We studied the exchange anisotropy of Ni-Fe/Co-Fe/Mn-Ir/Cu/buffer/Si multilayers using D.C magnetron sputtering technique. Generally, Ni-Fe/Mn-Ir/buffer(Cu)/Si multilayers cannot pin the ferromagnetic layer for the lower exchange biased field. We got $H_{ex}$ ex/ increased by two times, after using Cu/Ta as buffer layer to get larger grain size of Mn-Ir layer and inserting very thin Co-Fe layer between the Ni-Fe layer and the Mn-Ir layer to get improved grain-to-grain epitaxy relation at the interface between Ni-Fe layer and Mn-Ir layer. The variation of $H_{ex}$ by thickness of Mn-Ir layer in ferromagnete/Mn-Ir/buffer/Si multilayers is different to that in Mn-Ir/ferromagnete/buffer/Si multilayers, because the volume distribution of grain size of Mn-Ir layer and the exchange energy at the interface between the Mn-Ir and the ferromagnetic layers is different for stacking sequence.

• Journal of the Korean Magnetics Society
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• v.27 no.4
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• pp.123-128
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• 2017

The magnetic isotropy property from the magnetoresistance (MR) curve and magnetization (MH) loop for the PtMn based spin valve (SV) multilayer films fabricated with different the bottom structure after post-annealing treatment was investigated. The exchange biased coupling field ($H_{ex}$), coercivity ($H_c$), and MR ratio of Glass/Ta(10 nm)/CoFe(6 nm)/Cu(2.5 nm)/CoFe(3 nm)/Ta(4 nm) SV multilayer film without antiferromagnetic PtMn layer are 0 Oe, 25 Oe, and 3.3 %, respectively. MR curve for the Glass/Ta(10 nm)/CoFe(6 nm)/Cu(2.5 nm)/CoFe(3 nm)/PtMn(6 nm)/Ta(4 nm) SV multilayer film showed $H_{ex}=2Oe$, $H_c=316Oe$, and MR (%) = 4.4 % with one butterfly MR curve having by the effect of antiferromagnetic PtMn layer. MR curve for the dualtype Glass/Ta(10 nm)/CoFe(6 nm)/Cu(2.5 nm)/CoFe(3 nm)/PtMn(6 nm)/CoFe(3 nm)/Cu(2.5 nm)/CoFe(6 nm)/Ta(4 nm) SV multilayer film showed $H_c=37.5Oe$ and 386 Oe, MR = 3.5 % and 6.5 % with two butterfly MR curves and square-like hysteresis MH loops. The anisotropy property in CoFe spin valve-PtMn multilayer is neglected by the effects of a very small value of $H_{ex}$ and a very slightly shape magnetic anisotropy. This result is possible to explain the effect of magnetization configuration spin array of the bottom SV film and the top SV film of PtMn layer.

• Journal of the Korean Magnetics Society
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• v.8 no.4
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• pp.216-223
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• 1998

DC magnetron sputtering 방법에 의해 Corning glass 가판 위에 제작한 buffer/[CoFe/Cu]N 형태의 다층작막에 대하여 자기저항비의 비자성층 Cu두께, 기저층 종류(Fe, Cu, Cr, Ta)와 두께, Ardkqfur, 다층 층수 및 열처리 의존성을 조사하였다. 자기저항비는 비자성층 Cu 두께에 따라 진동하였다. 기저층 Fe 및 Cr의 두께가 60$\AA$이고, 층수 N=15, Ardkqfur 5mTorr에서 극대자기저항비 14%를 보였으며 25$0^{\circ}C$까지의 시료에 대한 열처리는 다층박막의 주기성을 유지한 채 더 큰 결정립을 갖게 하여 자기저항비는 증가하였으나 그 이상의 온도에서는 계면 혼합 및 계면 확산에 의한 감소를 나타내었다. Cr기저층 시료가 Fe 기저층 시료보다 열적안정성이 더 좋은 것을 알 수 있었다.

• Journal of the Korean Magnetics Society
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• v.4 no.4
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• pp.307-312
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• 1994

The magneto-optical Kerr effect due to the (Fe,Co)/(Pd,Pt,Cu,Ag) multilayer film is calculated considering of multiple reflection effect, and the calculated Kerr spectrum is compared to the reported experimental value. In case of Co/Pd, the reliance of composition and the variable tendency of magneto-optical Kerr rotation angle for Co thickness fully coresponds to experimantal and theoretical value. The theoretical Kerr spectrum of Fe/Cu and Fe/Ag multilayer films show the peaks near the Cu and Ag optical ansorption band in accordance with the experiment. But in case of Co/Pt, the increase tendency of Kerr rofation with decreasing wavelength reported by experiments could not be explained by the optical multiple interference. This difference of theoretical and experimental Kerr spectrum of Co/Pt film might be related with the change of electronic structure of Co and/or Pt from their bulk state.

• Journal of the Korean Magnetics Society
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• v.6 no.6
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• pp.411-416
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• 1996

We have studied the effect of a spin-dependence interface electron scattering on the giant magnetoresistance by adding a Fe magnetic material to the Co/Cu interfaces. The $Fe(50\;{\AA})/[Co(17\;{\AA})/Fe(t\;{\AA})/Cu(24\;{\AA})]_{20}$ multilayers are deposited on the Corning glass 2948 and 7059 substrates in a dc magnetron sputtering system. The magnetoresistance ratio is 22 % in the only Co/Cu multilayer, while it is increased to 26 % with inserted ultra thin Fe interface layer and reduced with increasing thickness of the Fe interface layer. It was investigated to the dependence of the magnetoresistance behaviors on annealing temperature. The magnetic properties of the multilayers were measured by vibrating sample magnetometer. Also, the structures and the surface roughness of samples were characterized by X-ray diffraction and atomic force microscope, respectively. The magnetoresistance ratio was increased to annealing temperature $300^{\circ}C$, but reduced at the temperature higher than $300^{\circ}C$ due to the interfacial diffuse.

• Proceedings of the Korean Magnestics Society Conference
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• 1997.11a
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• pp.20-21
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• 1997

• Journal of the Korean Magnetics Society
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• v.8 no.2
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• pp.79-85
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• 1998

The $[Ni_{80}Fe_{20}/Cu/Co/Cu]$ multilayers were grown by evaporation technique, and according to magnetic exchange coupling relation, magnetoresistance ratio and magnetization curve were studied by Co inserting $Ni_{80}Fe_{20}/Cu$ interface. Insertion of Co layer to the antiferromagnetically coupled system, i. e $t_{Cu} = 25\;{\AA}$, decrese the MR ratio contrary to previous reports. However the insertion to the ferromagneticalyl coupled $(t_{Cu} = 27\;{\AA})$ and the noncoupled $(t_{Cu} = 47\;{\AA})$ systems increase the ratio to 3.5 % and 6 % respectively. The results imply that the insertion change the magnetic exchange coupling state as well as the spin dependent scattering of conduction electrons. Besides, insertion of Co layer between Cu and $Ni_{80}Fe_{20}$ layer enhaces thermal stability to the 300 $^{\circ}C$, which indicates that insertion of Co has a role of the effective diffusion barrier.

• Journal of the Korean Magnetics Society
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• v.8 no.5
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• pp.282-287
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• 1998

Dependence of magnetoresistance on base pressure and deposition rates of each Fe, Co, Cu layers in the $Fe(50{\AA}/[Co(17{\AA})/Cu(24{\AA})]_20$ multilayer thin films, prepared by dc magnetron sputtering on Corning glass, were investigated. AFM analysis, X-ray diffraction analysis, vibrating sample magnetometer analysis, and magnetoresustance measurement (4-probe method) were performed. The multilayer films deposited under low base pressure increases magnetoresistance ratio by preventing oxidation. Annealing for the samples at a moderate temperature allowed larger textured grain with no loss in the periodicity. Magnetoresistance ratio of the annealed multilayers was increased due to the increase antiferromagnetically coupled fraction of the film after annealing. Optimization of deposition rate was greater than 1 $\AA$/s for Fe, and 2.8 $\AA$/s for Cu. Deposition rate of Co showed a tendency of increasing of magnetoresistance ratio due to the formation of flat magnetic layer in case of high deposition rate of Co.