• Proceedings of the Korean Magnestics Society Conference
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• 1998.05a
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• pp.52-53
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• 1998

• Proceedings of the Korean Magnestics Society Conference
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• 1997.11a
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• pp.32-33
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• 1997

• Proceedings of the Korean Magnestics Society Conference
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• 1997.05a
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• pp.44-45
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• 1997

• Journal of the Korean Magnetics Society
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• v.11 no.5
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• pp.211-216
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• 2001

Top synthetic spin valves wi th structure Ta/NiFe/CoFe/Cu/CoFe(Pl)/Ru/CoFe(P2)/FeMn/Ta on Si (100) substrate with SiO$_2$ of 1500 were prepared by dc magnetron sputtering system. We have changed only the thickness of the free layer and the thickness difference (Pl-P2) in the two ferromagnetic layers separated by Ru, and investigated the effect of magnetic film thickness on the GMR properties and the interlayer coupling field in a spin valve with a synthetic antiferromagnet. As thickness difference of pinned layer was decreased from +25 to -25 , MR ratio was decreased gradually. However, there was a dip zone indicating a big change of MR ratio around Pl = P2, which can be due to the large canting of pinned layers. The modified Neel model was suggested for the top synthetic spin valve to explain the interlayer coupling field according to the thickness change of ferromagnetic layers. The interlayer coupling field was decreased due to the magnetostatic coupling (orange peel coupling) as suggested by model. However, the interlayer coupling field was not explained at the dip zone by the modified Neel model. The deviation of modified Neel model at the dip zone could be due to the largely canting of the pinned layers as well, which depends on different thickness in synthetic antiferromagnetic structure.

• 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.

• Proceedings of the Korean Magnestics Society Conference
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• 2002.04a
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• pp.40-41
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• 2002

• 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.

• Proceedings of the Korean Magnestics Society Conference
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• 1996.10a
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• pp.26-27
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• 1996

• Journal of the Korean Magnetics Society
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• v.19 no.2
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• pp.52-56
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• 2009

Interlayer coupling field, coercivity, magnetoresitance ratio, and magnetic sensitivity depending on the thickness of free CoFe layer for the CoFe/Cu/CoFe/IrMn multilayer are investigated. In case of CoFe layer of $30\;{\AA}$ thickness for the CoFe(t)/Cu($25\;{\AA}$)/CoFe($60\;{\AA}$)/IrMn($80\;{\AA}$) multilayer with ferromagnet/non-magnet/ferromagnet structure induced by IrMn layer, the lowest coercivity and the highest magnetic sensitivity, which is contained soft magnetic property, are observed. On the other side, in case of CoFe layer of $90\;{\AA}$ thickness, there are the highest coercivity and the lowest magnetic sensitivity. The fabricated CoFe($30\;{\AA}$)/Cu($25\;{\AA}$)/CoFe($60\;{\AA}$)]/IrMn($80\;{\AA}$) spin valve device with $2{\times}8{\mu}m^2$ patterning size are measured by two probe method, which is selected the sensing current as the longitudinal direction and the easy axis as the transversal direction. The measuring magntoresistance ratio and magnetic sensitivity of GMR-SV device having the soft magnetic property are 3.0% and 0.3%/Oe, respectively.

• Journal of the Korean Magnetics Society
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• v.7 no.3
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• pp.152-158
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• 1997

NiFeCo/ Cu /Co trilayers were formed on 4$^{\circ}$ tilt-cut Si(111) substrates with a Cu(50$\AA$) underlayer and large-scaled test magnetoresistive RAM (MRAM) cells were fabricated using a conventional lithographic process. NiFeCo / Cu /Co trilayers deposited on the same templates without any applied magnetic field showed strong in plane uniaxial magnetic anisotropy and excellent magnetoresistive (MR) properties such as high MR ration and sensitivity within a low external magnetic field, which are suitable properties for a MRAM application. In order to obtain optimized MR results in NiFeCo /Cu /Co trilayers, the thickness of Cu spacer was varied. Interlayer coupling between two magnetic layers was observed and it was found that the MR properties were strongly dependent on the coupling force, especially near 20 $\AA$ of Cu spacer thickness. Test MRAM cells were fabricated using the optimized NiFeCo (60$\AA$)/ Cu (25$\AA$)/ Co (30$\AA$) trilayer thin films. With a 10 mA of sense current and 5$\times$$10^5$ of word current, 10 mV of signal output was obtained, which implies the strong potentials of NiFeCo/ Cu /Co trilayer thin films for a MRAM application.