• Bulletin of the Korean Chemical Society
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• v.25 no.2
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• pp.182-184
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• 2004

Fine $La_{2/3}Ca_{1/3}MnO_3$ nanocrystalline powders have been successfully prepared by modified citrate pyrolysis process. The obtained LCMO nanoscale grains have a mean particle size of about 30 nm under optimal treatment conditions. The particle size can be controlled by adjusting processing parameters, such as treatment temperature and calcination time. X-ray diffraction, SEM and magnetoresistance effect were employed to study the crystal structure, morphology and magnetic property of these nanosized powders. A novel MR effect (MR > 45% (0 K < T < 340 K)) at room temperature has been found.

• Journal of the Korean Society for Nondestructive Testing
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• v.28 no.6
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• pp.524-530
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• 2008

The spin valve tunneling magnetoresistance (SV-TMR) sensor performance is analyzed using Stoner-Wohlfarth model for the detection of eddy current signals in nondestructive testing applications. The SV-TMR response in terms of the applied AC magnetic field dominantly generates the second harmonic amplitude in hard axis direction. The second harmonic eddy current signal detection using SV-TMR sensor shows higher performance than that of the coil sensor at lower frequencies. The SV-TMR sensor with high sensitivity gives a good solution to improve the low frequency performance in comparison with the inductive coil sensors. Therefore, the low frequency eddy current techniques based on SV-TMR sensors are specially useful in the detection of hidden defects, and it can be applied to detect the deeply embedded flaws or discontinuities in the conductive materials.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.1076-1079
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• 2001

An anolmalous magnetoresistance effect has been theoretically studied at very low temperatures for composite normal metal conductors. This anomalous behavior is due to transverse Hall currents in the composite which would result in increased losses and higher effective resistance for the composite conductor. In this paper, transverse current flow and effective resistance with Cu-Al conductor configuration were analyzed using FEM(finite element method) for predicting the Hall losses to be resulted in anomalous magnetoresistance effect. And they are plotted three dimensionally to be visualized.

• Journal of Magnetics
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• v.14 no.4
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• pp.172-174
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• 2009

Nanolithography by atomic force microscope local oxidation was applied to the fabrication of planar-type Ni/Ni oxide/Ni junctions from 10 nm-thick Ni films. The junction characteristics were sensitive to the lithography conditions such as the bias voltage. Successful oxidation produced junctions of nonlinear current-voltage characteristics, implying the formation of oxide barriers. Magnetoresistance (MR) at low temperatures resembled that of spin valves.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.408-410
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• 1997

An anomalous magnetoresistance effect has been observed at very low temperatures for composite normal metal conductors. This anomalous behavior is due to transverse Hall currents in the composite which would result in increased $I^2R$ losses and a higher effective resistance for the composite conductor. In this paper, transverse current flow and effective resistance of Cu-Al double-strip was analyzed using finite element method for predicting the Hall losses to be resulted in anomalous magnetoresistance effect, and then be able to visualized.

• Journal of Magnetics
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• v.12 no.4
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• pp.152-155
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• 2007

Spin dependent transport was investigated in lateral $Py(Ni_{81}Fe_{19})/Au/Py$ spin valve devices. Clear spin valve effect was observed in conventional four-terminal measurement geometry. Higher resistance was found in antiparallel magnetization field of two Py electrodes which is determined by anisotropy magnetoresistance (AMR) measurements. The rectangular shape of spin signal together with good agreement of switching field convinces observed spin valve signal is resulted from effective spin injection and detection. The magnetoresistance ratio decays exponentially with channel length by which spin diffusion length of Au channel was estimated to be 76 nm.

• Journal of the Korean Magnetics Society
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• v.13 no.6
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• pp.243-245
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• 2003

The anomalous angular modulation of magnetoresistance in Co/Cu multilayers is explained assuming substrate-induced magnetic anisotropy. The magnetic parameters of Co/Cu multilayers is determined using angular modulation of magnetoresistance and theoretical model including substrate-induced anisotropy. This mechanism introduces a new possible way of modulating the giant magnetoresistance.

• Journal of Magnetics
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• v.6 no.4
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• pp.126-128
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• 2001

The effect of rapid thermal anneal (RTA) has been investigated on the properties of an FeMn exchange-biased magnetic tunnel junction (MTJ) using magnetoresistance and I-V measurements and transmission electron microscopy (TEM). The tunneling magnetoresistance (TMR) in an as-grown MTJ is found to be ∼27%, while the TMR in MTJs annealed by RTA increases with annealing temperature up to 300$\^{C}$, reaching ∼46%. A TEM image reveals a structural change in the interface of A1$_2$O$_3$layer for the MTJ annealed by RTA at 300$\^{C}$. The oxide barrier parameters are found to vary abruptly with annealing time within a few ten seconds. Our results demonstrate that the present RTA enhances the magnetoresistive properties of MTJs.

• Journal of the Korean Magnetics Society
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• v.3 no.4
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• pp.310-313
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• 1993

The effect of Ni content in Cu underlayer on the magnetoresistance of Cu/Co artificial superlattice has been investigated. As the content of Ni increased, the preferred orientation of artificial superlattice changed from fec (100) to fcc (111) due to the change of the preferred orientation of the underlayer. When the content of Ni was 6 %, 26.7 % of magnetoresistance with 175 Oe of saturation field could be obtained in ${[Cu(19\AA)/Co(30\AA)]}_{20}|Cu-6%Ni(200\AA)/Si$.

• Electrical & Electronic Materials
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• v.9 no.10
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• pp.1060-1065
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• 1996

We have studied the magnetoresistance phenomena on spin valve thin films of antiferromagnetic NiO/CoO. Interlayer coupling oscillates between the antiferrocoupling and ferrocoupling with the variation of Cu thickness. The exchange coupling strength between NiO (antiferromagnetic) and NiFe(ferromagnetic) as a function of NiO texture and interface roughness is investigated by CoO insertion. CoO has significantly higher anisotropy in the (111) plane and interface roughness. It seems that the MR-ratio is increased by CoO inserted films. From the AFM and XRD data, the increase of MR-ratio and exchange field is influenced by the roughness of CoO.