• Proceedings of the Korean Magnestics Society Conference
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• 2005.06a
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• pp.128-129
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• 2005

• Journal of the Korean Magnetics Society
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• v.23 no.6
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• pp.193-199
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• 2013

The regional distribution of magnetic isotropy depending on the post annealing condition for the dual-type structure GMR-SV (giant magnetoresistance-spin valve) of NiFe/Cu/NiFe/IrMn/NiFe/Cu/NiFe multilayer was investigated. The rotation of in-plane ferromagnetic layer induced by controlment of the post annealing temperature inside of the vacuum chamber. The magnetoresistive curves of a dual-type IrMn based GMR-SV depending on the direction of the magnetization easy axis of the free layer and the pinned layer are measured by between $0^{\circ}$ and $360^{\circ}$ angles for the applied fields. The optimum annealing temperature having a steady and isotropy magnetic sensitivity of 1.52 %/Oe was $107^{\circ}C$ in the rotational section of $0{\sim}90^{\circ}$. By investigating the switching process of magnetization for an arbitrary measuring direction, the in-plane orthogonal magnetization for the dual-type GMR-SV multilayer can be used by a high sensitive biosensor for detection of magnetized micro-beads.

• Journal of the Korean Magnetics Society
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• v.16 no.3
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• pp.157-162
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• 2006

In this study, a high sensitive giant magnetoresistance-spin valve (GMR-SV) bio-sensing device with high linearity and very low hysteresis was fabricated by photolithography and ion beam deposition sputtering system. Detection of the Fe-hemoglobin inside in a red blood and magnetic nanoparticles using the GMR-SV bio-sensing device was investigated. Here a human's red blood includes hemoglobin, and the nanoparticles are the Co-ferrite magnetic particles coated with a shell of amorphous silica which the average size of the water-soluble bare cobalt nanoparticles was about 9 nm with total size of about 50 nm. When 1 mA sensing current was applied to the current electrode in the patterned active GMR-SV devices with areas of $5x10{\mu}m^2 $ and $2x6{\mu}m^2 $, the output signals of the GMRSV sensor were about 100 mV and 14 mV, respectively. In addition, the maximum sensitivity of the fabricated GMR-SV sensor was about $0.1{\sim}0.8%/Oe$. The magnitude of output voltage signals was obtained from four-probe magnetoresistive measured system, and the picture of real-time motion images was monitored by an optical microscope. Even one drop of human blood and nanopartices in distilled water were found to be enough for detecting and analyzing their signals clearly.

• Journal of the Korean Magnetics Society
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• v.17 no.4
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• pp.172-177
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• 2007

In order to detect of the magnetic property in the cell unit, we studied the GMR-SV (giant magnetoresistance-spin valves) biosensor, which was depended on the micro patterned features according to two easy directions of longitudinal and transversal axes. Here, the multi layer structure was glass/NiO/NiFe/CoFe/Cu/CoFe/NiFe. The uniaxial anisotropy direction was applied to the patterned biosensor during the deposition and vacuum post-annealing at $200^{\circ}C$ under the magnitude of 300 Oe, respectively. Considering the magnetic shape anisotropy effect, the size of micro patterned biosensor was a $2{\times}5{\mu}m^2$ after the photo lithography process. By our experimental results, we confirmed that the best condition of GMR-SV biosensor should be the same direction of the axis sensing current and the easy axis of pinned NiO/NiFe/CoFe triple layer oriented to the width direction of device, and the direction of the easy axis of free CoFe/NiFe bilayer was according to the longitudinal direction of device.

• Proceedings of the Korean Magnestics Society Conference
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• 2009.05a
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• pp.133-134
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• 2009

• Proceedings of the Korean Magnestics Society Conference
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• 2007.12a
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• pp.192-194
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• 2007

• Proceedings of the Korean Magnestics Society Conference
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• 2012.05a
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• pp.63-64
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• 2012

• Journal of the Korean Magnetics Society
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• v.25 no.5
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• pp.149-155
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• 2015

The ECR (Electron Cyclotron Resonance) Ar ion milling was manufactured to fabricate the device of thin film. The ECR ion milling system applied to the device etching operated by a power of 600W, a frequency of 2.45 GHz, and a wavelength of 12.24 cm and transferred by a designed waveguide. In order to match one resonant frequency, a magnetic field of 908 G was applied to a cavity inside of ECR. The Ar gas intruded into a cavity and created the discharged ion beam. The surface of target material was etched by the ion beam having an acceleration voltage of 1000 V. The formed devices with a width of $1{\mu}m{\sim}9{\mu}m$ on the GMR-SV (Giant magnetoresistance-spin valve) multilayer after three major processes such as photo lithography, ion milling, and electrode fabrication were observed by the optical microscope.

• 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.20 no.2
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• pp.41-44
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• 2010

The Cu thickness dependence of magnetic sensitivity for the NiFe/Cu/NiFe/IrMn spin valve multilayer was investigated. The magnetic properties measured by minor MR curves for the Ta(5 nm)/NiFe(8 nm)/Cu(3.5 nm)/NiFe(4 nm)/IrMn(8 nm)/Ta(2.5 nm) multilayer is MR = 1.46 %, MS = 2.0 %/Oe, $H_c\;=\;2.6\;Oe$, and $H_{int}\;=\;0.1\;Oe$. The magnetic sensitivities of GMR-SV devices with ten different widths and a same length of $4.45\;{\mu}m$ by fabricated by photo lithography decreased from 0.3 %/Oe to 0.06%/Oe as from a width of $10\;{\mu}m$ to $1\;{\mu}m$.