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Rotation Effect of In-plane FM layer on IrMn Based GMR-SV Film
Purevdorj Khajidmaa,Jong-Gu Choi,Sang-Suk Lee 한국자기학회 2017 Journal of Magnetics Vol.22 No.1
The magnetoresistance (MR) properties of antiferromagnetic (AFM) IrMn based giant magnetoresistance-spin valve (GMR-SV) was investigated in view point of the artificial rotation effect of ferromagnetic (FM) layer in the plane induced by an applied field during the post annealing temperature. The MR curves measured with an azimuthal angle region of φ = 0°-360° are depended on the annealing temperature and the magnetization easy axis of two free NiFe layers and two pinned NiFe layers in dual-type GMR-SV film. Especially, the annealing temperature and sample rotation angle(θ ) maintained to the magnetic sensitivity (MS) of 1.4 %/Oe with an isotropic region angle of 110° are 100 °C and 90°, respectively.
이중구조 거대자기저항-스핀밸브 박막의 자기등방성 영역분포에 관한 연구
카지드마(Purevdorj Khajidmaa),이상석(Sang-Suk Lee) 한국자기학회 2013 韓國磁氣學會誌 Vol.23 No.6
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˚ and 360˚ angles for the applied fields. The optimum annealing temperature having a steady and isotropy magnetic sensitivity of 1.52 %/Oe was 107℃ in the rotational section of 0~90˚. 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.
NiFe/Cu/NiFe 박막과 YBa₂Cu₃O<SUB>7−x </SUB>박막 사이 NiO 층의 두께에 따른 전류전달효과에 의한 음의 자기저항비 특성 연구
카지드마(Purevdorj Khajidmaa),강병욱(Byeong-Uk Kang),최종구(Jong-Gu Choi),이상석(Sang-Suk Lee),양우일(Woo-Il Yang) 한국자기학회 2019 韓國磁氣學會誌 Vol.29 No.2
The magnetoresistance (MR) curves of giant magnetoresistive-spin valve (GMR-SV) multilayer on Corning glass and sapphire/high-temperature superconductor (HTS) YBa₂Cu₃O<SUB>7−x</SUB> (YBCO) film fabricated by magnetron sputtering were compared and analyzed. Hybrid type HTS and GMR-SV multilayer film with antiferromagnetic NiO thickness of 10 nm has a negative MR ratio of−7.7 %, an exchange coupling field (H<SUB>ex</SUB>) of 120 Oe, a coercive force (H<SUB>c</SUB>) of 125 Oe, respectively. However, there is exist a positive MR ratio of +7.3 % in case of NiO thickness of 60 nm. The glass/NiO/NiFe/Cu/NiFe/Ta multilayer showed linear current-voltage (IV) curve, but the Al₂O₃/YBCO/NiO(10 nm, 60 nm)/NiFe/Cu/NiFe/Ta multilayer showed a nonlinear I-V curve in which the resistance value of 1.15 Ω and 59.4 Ω decreased to 1.02 Ω and 50.2 Ω when the current of 15.7 mA increased to 1.67 mA, respectively. This results are explained by the current transfer effect in the 4-probe electrode measurement method occurred when the resistance of the YBCO film is 0.
ECR-이온 밀링을 이용한 의료용 네블라이저 백금(Pt) 메쉬 제작 특성
안명천,박철우,purevdorj khajidmaa,벌러르마,이원형,홍기민,이상석 한국물리학회 2015 새물리 Vol.65 No.11
A Pt mesh with a foil thickness of 30 μm and a hole diameter of 3.5 μm for a medical respiratory nebulizer was fabricated by using the electron cyclotron resonance (ECR) Ar-ion milling method. The surface morphology of the commercial Pt mesh was investigated by using scanning electron microscopy. Holes in the Cu foil were first formed by using the chemical wet etching method, and Pt was then electroplated on to the surface. The result for the commercial mesh was compared with the result for the mesh fabricated by using a physical dry etching method making use of ECR Ar-ion milling. With photolithography and 10 h of ECR Ar-ion milling, holes of 3.5 μm in diameter and 110 μm in pitch were obtained. Uniform holes with clear surface morphologies could easily be observed on the Pt mesh by using an optical microscope. 직경 3.5 μm 홀 (hole)이 패터닝된 두께 30 μm인 Pt 호일에 ECR Ar 이온 밀링법을 이용하여 호흡기 질환 질병치료용 네블라이저 메쉬를 제작하였다. 기존 네블라이저 제품의 Pt메쉬 표면형상구조를 SEM을 통해 분석하였다. 광 리소그래피 공정으로 패터닝된Cu 호일에 화학적 Wet 에칭 방법으로 홀을 형성한 후 전기도금법으로 Pt 박막을 입혀서 메쉬를 제작하여 물리적 Dry에칭 방법으로 제작한 것과 비교하였다. 광 리소그래피 공정으로 홀의 직경과 피치를 각각 3.5 μm, 110 μm로 하여 패터닝된 Pt 호일을 전자사이클로트론 공명 Ar-ion 밀링을 약 10시간 동안 에칭하였다. 제작된 Pt 메쉬는 깨끗한 표면형상을 유지하면서 균일한 홀 직경인 3.5 μm 크기가 광학현미경으로 관찰되었다.
GMR-SV 박막내 미크론 크기의 홀 형성을 이용한 교환결합세기와 보자력 특성연구
벌러르마(Munkhbat Bolormaa),카지드마(Purevdorj Khajidmaa),황도근(Do-Guwn Hwang),이상석(Sang-Suk Lee),이원형(Won-Hyung Lee),이장로(Jang-Roh Rhee) 한국자기학회 2015 韓國磁氣學會誌 Vol.25 No.4
The holes with a diameter of 35 μm inside the GMR-SV (giant magnetoresistance-spin valve) film were patterned by using the photolithography process and ECR (electron cyclotron resonance) Ar-ion milling. From the magnetoresistance curves of the GMR-SV film with holes measuring by 4-electrode method, the MR (magnetoresistance ratio) and MS (magnetic sensitivity) are almost same as the values of initial states. On other side hand, the H<SUB>ex</SUB> (exchange bias coupling field) and H<SUB>c</SUB> (coercivity) dominantly increased from 120 Oe and 10 Oe to 190 Oe and 41 Oe as increment of the number of holes inside GMR-SV film respectively. These results were shown to be attributed to major effect of EMD (easy magnetic domian) having a region positioned between two holes perpendicular to the sensing current. On the basis of this study, the fabrication of GMR-SV applying to the hole formation improved the magnetoresistance properties having the thermal stability and durability of bio-device.
거대자기저항-스핀밸브와 고온초전도체 사이에 있는 틈 층에 의한 전류전달효과 특성연구
양우일(Woo-Il Yang),강병욱(Byeong-Uk Kang),최종구(Jong-Gu Choi),카지드마(Purevdorj Khajidmaa),이상석(Sang-Suk Lee) 한국자기학회 2018 韓國磁氣學會誌 Vol.28 No.5
A giant magnetoresistive - spin valve (GMR-SV) NiFe/CoFe/Cu/CoFe/IrMn/Ta multilayer film was fabricated by ion beam deposition on a commercial high - temperature superconductor Y₁Ba₂Cu₃O<SUB>7 - x</SUB> (YBCO) film. The thickness of the hybrid YBCO thin film was 300 nm and one of the antiferromagnetic IrMn-based GMR-SV thin film was 55 nm. The superconductor characteristics of the YBCO thin films were confirmed by the R-T curve measured with 4-terminal and the Q-T and I-V curves measured with a microwave cavity resonator. In particular, the phenomenon of negative magnetoresistance (MR) ratio in the reversed MR curve of -7.4% is explained by the current transfer effect from the MR and the I-V curves measured by the 2-, 3-, and 4-probe methods at 77 K below the critical temperature. It was also confirmed by SEM image that a gap layer of 9.3 nm was present between the YBCO film and the GMR-SV multilayer. The residual resistance of 0.456 Ω was measured due to the presence of the gap layer and the difference in current transfer was caused by the superconductor depending on the change of the spin magnetization array configuration of GMR-SV.