• Title/Summary/Keyword: GMR

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Electrodeposition of GMR Ni/Cu Multilayers in a Recirculating Electrochemical Flow Reactor

  • Rheem, Young-Woo
    • Korean Journal of Materials Research
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    • v.20 no.2
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    • pp.90-96
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    • 2010
  • The recirculating electrochemical flow reactor developed at UCLA has been employed to fabricate nanostructured GMR multilayers. For comparison, Ni/Cu multilayers have been electrodeposited from a single bath, from dual baths and from the recirculating electrochemical flow reactor. For a magnetic field of 1.5 kOe, higher GMR (Max. -5%) Ni/Cu multilayers with low electrical resistivity (< $10\;{\mu}{\Omega}{\cdot}cm$) were achieved by the electrochemical flow reactor system than by the dual bath (Max. GMR = -4.2% and < $20\;{\mu}{\Omega}{\cdot}cm$) or the single bath (Max. GMR = -2.1% and < $90\;{\mu}{\Omega}{\cdot}cm$) techniques. Higher GMR effects have been obtained by producing smoother, contiguous layers at lower current densities and by the elimination of oxide film formation by conducting deposition under an inert gas environment. Our preliminary GMR measurements of Ni/Cu multilayers from the electrochemical flow reactor obtained at low magnetic field of 0.15 T, which may approach or exceed the highest reported results (-7% GMR) at magnetic fields > 5 kOe.

New Macroscopic Ferrimagnets in the System Co-TbN

  • Kim, Tae-Wan;Oh, Jung-Keun
    • Journal of Magnetics
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    • v.13 no.1
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    • pp.11-18
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    • 2008
  • This study examines a new macroscopic ferrimagnet, Co-TbN. This ferrimagnet, consisting of two metallic phases, Co and TbN, demonstrated the typical macroscopic ferrimagnet properties of a magnetic compensation point and a negative giant magnetoresistance (GMR). The Co-TbN system with 32% TbN composition showed 0.72% GMR in magnetic fields up to 8 kOe at room temperature and 9% GMR in 40 kOe at 250 K. In the Co-TbN system, GMR exhibited a different dependence on temperature from that of ordinary GMR materials whose negative magnetoresistance decreases with increasing temperature. In contrast to ordinary GMR materials whose negative magnetoresistance decreases with increasing temperature, the GMR effect in the Co-TbN system increased with increasing temperature, due to the increase of ferromagnetic alignment of the Co and TbN in the magnetic field caused by the decreased exchange coupling with increasing temperature.

GMR Sensor Applicability to Remote Field Eddy Current Defect Signal Detection in a Ferromagnetic Pipe (강자성 배관의 원격장 와전류 결함 신호 검출에 GMR Sensor의 적용성 연구)

  • Park, Jeong Won;Park, Jae Ha;Song, Sung Jin;Kim, Hak Joon;Kwon, Se Gon
    • Journal of the Korean Society for Nondestructive Testing
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    • v.36 no.6
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    • pp.483-489
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    • 2016
  • The typical methods used for inspecting ferromagnetic pipes include the ultrasonic testing (UT) contact method and the following non-contact methods: magnetic flux leakage (MFL), electromagnetic acoustic transducers (EMAT), and remote field eddy current testing (RFECT). Among these methods, the RFECT method has the advantage of being able to establish a system smaller than the diameter of a pipe. However, the method has several disadvantages as well, including different sensitivities and difficult-to-repair coil sensors which comprise its array system. Therefore, a giant magneto-resistance (GMR) sensor was applied to address these issues. The GMR sensor is small, easy to replace, and has uniform sensitivity. In this experiment, the GMR sensor was used to measure remote field and defect signal characteristics (in the axial and radial directions) in a ferromagnetic pipe. These characteristics were measured in an effort to investigate standard defects at changing depths within a pipe. The results show that the experiment successfully demonstrated the applicability of the GMR sensor to RFECT signal detection in ferromagnetic pipe.

Magnetoresistance of Single-type and Dual-type GMR-SV Multilayer Thin Films with Top and Bottom IrMn Layer (상부와 하부 IrMn층을 갖는 단일구조 및 이중구조 거대자기저항-스핀밸브 다층박막의 자기적 특성 비교 분석)

  • Choi, Jong-Gu;Kim, Su-Hee;Choi, Sang-Heon;Lee, Sang-Suk
    • Journal of the Korean Magnetics Society
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    • v.27 no.4
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    • pp.115-122
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    • 2017
  • The antiferromagnet IrMn based four different GMR-SV multilayers on Corning glass were prepared by using ion beam deposition and DC magnetron sputtering system. The magnetoresistance (MR) properties for single-type and dual-type GMR-SV multilayer films were investigated through the measured major and minor MR curves. The exchange bias coupling field ($H_{ex}$) and coercivity ($H_c$) of pinned layer, the $H_c$ and interlayer exchange coupling field ($H_{int}$) of free layer for the dual-type structure GMR-SV multilayer films consisted of top IrMn layer were 410 Oe, 60 Oe, 1.6 Oe, and 7.0 Oe, respectively. The minor MR curve of two free layers was performed the squarelike feature having a MR ratio of 8.7 % as the sum of 3.7 % and 5.0 %. The value of average magnetic field sensitivity (MS) was maintained at 2.0 %/Oe. Also, the magnetoresistance properties of the single-type and dual-type structure GMR-SV multilayer films consisted of bottom IrMn layer were decreased more than those of top IrMn layer. Two antiparallel states of magnetization spin arrays of the pinned and free layers in the dual-type GMR-SV multilayer films occurred the maximum MR value by the effect of spin dependence scattering.

Giant magnetoresistance of new macroscopic ferrimagnets in the system Co-TbN

  • Kim, T. W.;H. B. Chung
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1998.06a
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    • pp.45-48
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    • 1998
  • We first report the GMR effect of new macroscopic ferrimagnet, Co-TbN. The Co-TbN system demonstrates typical macroscopic ferrimagnet properties which are a magnetic compensation Point and negative giant magnetoresistance (GMR) which is caused by the spin scattering contribution quite different from those of ordinary GMR materials. The Co-TbN system with 32 % TbN composition showed 0.72 % GMR in fields up to 8 kOe at room temperature and 9 % GMR at 250 K in 40 kOe. The GMR effect in the Co-TbN system increases with increasing temperature, which is due to the increase of ferromagnetic alignment of the Co and TbN in a field caused by the decrease of exchange coupling by temperature.

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Detection Property of Red Blood Cell-Magnetic Beads Using Micro Coil-Channeland GMR-SV Device (마이크로 코일-채널과 GMR-SV 소자를 이용한 적혈구-자성비드 검출 특성연구)

  • Park, Ji-Soo;Kim, Nu-Ri;Jung, Hyun-Jun;Lee, Sang-Suk
    • Journal of the Korean Magnetics Society
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    • v.25 no.1
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    • pp.16-21
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    • 2015
  • The micro device, coil, and channel for the biosensor integrated with the GMR-SV device based on the antiferromagnetic IrMn layer was fabricated by the light lithography process. When RBCs coupled with several magnetic beads with a diameter of $1{\mu}m$ passed on the micro channel, the movement of $RBC+{\mu}Beads$ is controlled by the electrical AC input signal. The $RBC+{\mu}Beads$ having a micro-magnetic field captured above the GMR-SV device is changed as the output signals for detection status. From these results, the GMR-SV device having the width magnitude of a few micron size can be applied as the biosensor for the analysis of a new magnetic property as the membrane's deformation of RBC coupled to magnetic beads.

Detection Characteristics of a Red Blood Cell Coupled with Micron Magnetic Beads by Using GMR-SV Device (GMR-SV 소자를 이용한 미크론 자성비드와 결합된 적혈구 검출 특성 연구)

  • Lee, Jae-Yeon;Kim, Moon-Jong;Lee, Sang-Suk;Rhee, Jin-Kyu
    • Journal of the Korean Magnetics Society
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    • v.24 no.4
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    • pp.101-106
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    • 2014
  • The glass/Ta(5.8 nm)/NiFe(5 nm)/Cu(2.3 nm)/NiFe(3 nm)/IrMn(12 nm)/Ta(5.8 nm) GMR-SV (giantmagneto-resistance-spin valve) multilayer structure films with a magnetoresistance ratio (MR) of 5.0 % and a magnetic sensitivity (MS) of 1.5%/Oe was deposited by dc magnetron sputtering method. Also, GMR-SV device having a width of $7{\mu}m{\sim}8{\mu}m$ similar to the diameter of RBC (red blood cell) was fabricated by the light lithography process. When RBCs coupled with several magnetic beads with a diameter of $1{\mu}m$ dropped upon the GMR-SV device having MR = 1.06% and MS = 0.3 %/Oe, there is observed the variation of about included of a resistance value of ${\Delta}R=0.4{\Omega}$ and ${\Delta}MR=0.15%$ around a external magnetic field of -0.6 Oe. From these results, the GMR-SV device having the width magnitude of a few micron size can be applied as the biosensor for the analysis of a new magnetic property of hemoglobin inside of RBC combined to magnetic beads.

Properties of Exchange Bias Coupling Field and Coercivity Using the Micron-size Holes Formation Inside GMR-SV Film (GMR-SV 박막내 미크론 크기의 홀 형성을 이용한 교환결합세기와 보자력 특성연구)

  • Bolormaa, Munkhbat;Khajidmaa, Purevdorj;Hwang, Do-Guwn;Lee, Sang-Suk;Lee, Won-Hyung;Rhee, Jang-Roh
    • Journal of the Korean Magnetics Society
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    • v.25 no.4
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    • pp.117-122
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    • 2015
  • The holes with a diameter of $35{\mu}m$ 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 $H_{ex}$ (exchange bias coupling field) and $H_c$ (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.

Implementation of Highly Efficient GMR Color Filter using Asymmetric Si3N4 Gratings (비대칭 Si3N4 격자를 사용한 고효율 GMR 컬러 필터의 구현)

  • Ho, Kwang-Chun
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.17 no.1
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    • pp.225-230
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    • 2017
  • In this paper, a highly efficient GMR(guided-mode resonant) color filter is proposed and implemented. The GMR color filter consists of $Si_3N_4/air$ layers containing complementary fixed and mobile gratings. The device is designed using RETT(rigorous equivalent transmission-line theory) and a grating structure operating in subwavelength. The numerical result reveals that the color filter has a tuning capability of about 35 nm over the $0.45{\mu}m{\sim}0.55{\mu}m$ range for blue-green color and across $0.6{\mu}m{\sim}0.7{\mu}m$ range for red color. Furthermore, The color filters have a spectral bandwidth of about 8 nm with efficiencies of 99%, 98%, and 99% at the center wavelength of blue, green, and red color, respectively, and these are higher efficiencies than reported in the literature previously.