• Journal of Magnetics
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• v.2 no.1
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• pp.28-33
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• 1997

Very large in electrical resistivity by several orders of magnitude is obtained when an external magnetic field is applied to the colossal magnetoresistnace (CMR) materials such as La-Ca-Mn-O. The magnetoresistance is strongly temperature-dependent, and exhibits a sharp peak below room temperature, which can be shifted by adjusting the composition or processing parameters. The control of lattice geometry or strain, e.g., by chemical substitution, epitaxial growth or post-deposition anneal of thin films appears to be crucial in obtaining the CMR properties. The orders of magnitude change in electrical resistivity could be useful for various magnetic and electric device applications. .

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.950-953
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• 1999

Spin tunneling giant magnetoresistance effect was studied to utilize in the application of random access memory. Ferromagnetic/Insulator/Ferromagnetic films were sputtered on glass substrates and perpendicular current was applied. Measurements of magneto- resistance of the junction showed 8.6% of MR ratio. Voltage output depends on the magnetization directions of the write line and read line, thus enabling the system to be used as a random access memory

• Proceedings of the Korean Magnestics Society Conference
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• 2002.12a
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• pp.80-81
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• 2002

MR(magnetoresistance)은 물질의 저항이 자기장에 의해 변하는 물리적인 변화(physical MR)와 기하학적인 요소, 즉 sample의 모양과 contact의 크기 등에 의한 변화(geometric MR)의 합으로 나타낸다.[1] Physical MR은 자기장에 따른 비저항 또는 이동도(mobility)의 변화로 나타낼 수 있고, geometric MR은 로렌츠 힘에 의해 전류의 흐르는 방향이 변하면서 일어난다. 본 연구에서는 physical MR이 거의 없는 반도체(InAs)와 비교적 큰 physical MR을 가지는 반도체(HgCdTe)의 geometric factor를 고려한 MR의 향상에 대하여 연구하였다. (중략)

• Proceedings of the Korean Magnestics Society Conference
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• 2002.12a
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• pp.152-153
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• 2002

The report on large tunneling magnetoresistance (TMR) at room temperature in magnetic tunnel junctions (MTJ), composed of two ferromagnetic electrodes separated by a thin insulating barrier, has ignite the intensive research both from scientific and technological points of view. A simple model proposed by Juliere has explained the observed TMR surprisingly well, where the TMR is expressed in terms of the spin polarization P of the ferromagnetic electrodes. (omitted)

• Proceedings of the Korean Magnestics Society Conference
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• 2002.12a
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• pp.72-73
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• 2002

MR(Magnetoresistance)현상이란 인가된 자장에 의해 저항이 변하는 현상이다. 이 현상은 여러 측면에서 연구되고 있고 그 중 TMR(Tunneling Magnetoresistance)현상은 sensor, head, memory device의 적용에 대한 연구가 진행 중에 있다. 특히 memory 소자 측면에서 MRAM은 현재 사용되고 있는 DRAM이나 SRAM들과는 달리 비휘발성과 기록밀도의 고집적 등 많은 장점을 갖는 소자로써 연구되고 있다. (중략)

• Journal of Magnetics
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• v.3 no.1
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• pp.36-38
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• 1998

We measure the magnetoresistance (MR) of sputtered Permalloy ($Ni_{83}Fe_{17}$) films with external strains produced by piezoelectric tranducer actuators. We observe that the MR raito was increased by 2.3 times by a compressive strain of $3.5{\times}10^{-4}$ compared to that of the as-deposited film. Tensile strains and compressive strains reduced the MR ratio. These observations suggest that it is possible to tune the MR properties through the use of the external strains. We expect to apply the results for the multi-head magnetic recorders with selectively activated recording heads.

• Journal of the Korean Magnetics Society
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• v.12 no.6
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• pp.201-205
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• 2002

The tunneling magnetoresistance (TMR) of a ramp-edge type junction has been studied. The samples with a structure of NiO(60)/Co(10)/NiO(60)/Si$_3$N$_4$(2-6)/NiFe(10) (nm) were prepared by the sputtering and etched by the electron cyclotron (ECR) argon ion milling. Nonlinear I-V characteristics was obtained from a ramp-type tunneling junctions having the dominant difference between zero and ＋90 Oe perpendicular to the junction edge line. The voltage dependence of TMR was stable up to a bias volt of $\pm$10 V with a TMR ratio of about -10%, which may be very peculiar magnetic tunneling properties with asymmetric tunneling process between wedge Co pinned layer and NiFe free layer.

• Journal of the Korean Magnetics Society
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• v.23 no.3
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• pp.98-103
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• 2013

The magnetic easy axis of the ferromagnetic layer for the dual-type GMR-SV (giant magnetoresistance-spin valve) having NiFe/Cu/NiFe/IrMn/NiFe/Cu/NiFe multuilayer structure controlled by the post annealing treatment. The magnetoresistive curves of a dual-type IrMn based GMR-SV depending on the direction of the magnetic easy axis of the free and the pinned layers are measured by the different angles for the applied fields. By investigating the switching process of magnetization for an arbitrary measuring direction, the optimum annealing temperature having a steady and isotropy magnetic sensitivity of 2.0 %/Oe was $105^{\circ}C$. This result suggests that the in-plane orthogonal magnetization for the dual-type GMR-SV film can be used by a high sensitive biosensor.

• Journal of the Korean Magnetics Society
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• v.7 no.1
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• pp.31-37
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• 1997

The magnetoresistance and the saturation field behavior of the Co-Ag nano granular films as a function of the composition and the ferromagnetic underlayer and overlayermaterials were investigated. The maximum magnetoresistance of 23% and the saturation field of 2.3 kOe at room temperature were obtained in the as-deposited 3000$\AA$ $Co_{30}Ag_{70}$ single alloy films. The magnetoresistance and the saturation field of 100$\AA$ $Co_{30}Ag-{70}$ alloy film were 3.65 % and 3.0 kOe respectively. Those of the sandwiched films with 200$\AA$ Fe were 3.3 % and 1.23 kOe respectively. The saturation field of the sandwiched alloy films could be reduced by the exchange coupling between the ferromagnetic layers and the alloy layer. The effective depth of the exchange coupling was approximately 150$\AA$ in each Fe layer. Among the Fe, Co, and FeNi, the most effective materials to reduce the saturation field of the sandwiched alloy films was Fe.

• Journal of the Korean Magnetics Society
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• v.11 no.3
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• pp.97-103
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• 2001

Polycrystalline thin films of La$_{2}$3/Sr$_{1}$3/MnO$_3$(LSMO) were prepared by water-based sol-gel processing on thermally oxidized Si(100) substrate. The thickness dependence of the low-field tunnel-type magnetoresistance properties at room temperature was studied. Tunnel-type magnetoresistance at low-field is found to be strongly dependent on film thickness. Maximum value of tunnel-type magnetoresistance of LSMO thin films was appeared at the film thickness of ~1500 $\AA$. This behavior can be explained in terms of dead layer between LSMO thin film and Si(100) substrate and thermal lattice strain effect in the LSMO thin films.