• Title/Summary/Keyword: magnetic hysteresis measurement

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Manufacture and Evaluation of Reference Samples for Low Magnetic Moment (저자기 모멘트용 표준시료 제작 및 성능평가)

  • Park, I.W.;Hong, Y.S.;Kim, Y.M.;Yoon, H.;Lee, K.J.;Cho, S.H.
    • Journal of the Korean Magnetics Society
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    • v.18 no.1
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    • pp.1-8
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    • 2008
  • We have manufactured and evaluated reference samples for the use of low magnetic moment measurements. Before the measurements, SQUID magnetometers were magnetically shielded from external magnetic noise. We considered the purity including magnetic impurities, the optimum thickness, the modification method, and the shape in the preparation of the samples. Three paramagnetic polycrystaline metal plates of Ti, W, and Al with the area of $4mm{\times}6mm$ were prepared finally. The magnetic moments of these three samples are measured very linear up to the field of 5 T without magnetic hysteresis. The temperature deviated ratios of the magnetic moments for Ti, Al, and W from 290 K to 310 K are 0.7, 1.5, and 0.1 %, respectively. The measured magnetic moments for Ti and W samples by our research team are very well agreeable with those by two SQUID magnetometers and a VSM at Quantum Design via international round robin test. The results suggest that the prepared reference samples are well suited for the use in the low magnetic moment measurement with SQUID based magnetometers.

Reduction Chattering Error of Reed Switch Sensor for Remote Measurement of Water Meter (Reed Switch 센서를 이용한 원격 검침용 상수도 계량기에서 Chattering 오차 감소 방안 연구)

  • Ayurzana, Odgerel;Kwon, Jong-Won;Park, Yong-Man;Koo, Sang-Jun;Kim, Hie-Sik
    • Proceedings of the KIEE Conference
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    • 2007.04a
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    • pp.377-379
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    • 2007
  • To reduce the chattering errors of reed switch sensors used for automatic remote measurement of water supply system, a reed switch sensor was analyzed and improved. The operation of reed switch sensors can be described as a mechanical contact by approximation of permanent magnet piece to generate an electrical pulse. The reed switch sensors are used in measurement application by detecting the rotational or translational displacement. To apply for flow measurement devices, the reed switch sensors should keep high reliability. They are applied for the electronic digital type of water flow meters. The reed switch sensor is just installed simply on the mechanical type flow meter. A small magnet is attached on a pointer of the water meter counter rotor. Inside the reed sensor, two steel leaf springs make mechanical contact and apart as rotation of flow meter counter. The counting electrical contact pulses can be converted as the water flow amount. The MCU sends the digital flow rate data to the server using the wireless communication network. But it occurs data difference or errors by chattering noise. The reed switch sensor contains chattering error by it self at the force equivalent position. The vibrations such as passing car near to the switch sensor installed location. In order to reduce chattering error, most system uses just software methods for example using filter and also statistical calibration methods. The chattering errors were reduced by changing leaf spring structure using mechanical hysteresis characteristics.

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Development of High-Density Information Storage Media by Employing the Six Sigma Methodology (식스 시그마 기법을 활용한 고밀도 정보저장 매체 개발)

  • Lee, Myung-Bok
    • Journal of the Korea Convergence Society
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    • v.9 no.9
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    • pp.41-46
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    • 2018
  • Six sigma methodology is the management tools not only can cause productivity enhancement through the quality control and cost reduction of products and services but also can be applied to various activities of corporates such as research and development. Development of high-density information storage media and devices is indispensible to accomplish the information convergence era. In this paper, we report the case of applying six sigma methodology and tools to the development project of high-density information storage media. The standard DMAIC process was applied to the project and pursuing goals and tools and results in each stage were explained in detail. By adopting the methodology, we could establish fabrication methods of information storage media of recording density higher than $250Gb/in^2$ with high uniformity and reproducibility. The magnetic property and performance of fabricated media were confirmed through measurement of the magnetic hysteresis curve.

Preparation of Biopolymer coated Magnetite And Magnetic Biopolymer Microsphere Particles for Medical Application (의학적 응용을 위한 생체 고분자로 피복 된 자성 나노 입자와 미소구체의 제조)

  • Ko, Sang-Gil;Cho, Jun-Hee;Ahn, Yang-kyu;Song, Ki-Chang;Choi, Eun-Jung
    • Journal of the Korean Magnetics Society
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    • v.16 no.4
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    • pp.221-227
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    • 2006
  • We have synthesized uniform nanometer sized magnetite particles using chemical coprecipitation technique through a sonochemical method with surfactant such as oleic acid. Magnetite phase nanoparticles could be observed from X-ray diffraction. Magnetite nanoparticles is surface phase morphology and biopolymer-microspheres for Application Medical. Magnetite nanoparticles coated biopolymer. Atomic Force Microscope (AFM) was used to image the coated nanoparticles. Magnetic colloid suspensions containing particles with sodium oleate, chitosan and $\beta$-glucan have been prepared. The morphology of the magnetic biopolymer microsphere particles were characterized using optical microscope. Magnetic hysteresis measurement were performed using a superconducting quantum interference device (SQUID) magnetometer at room temperature to investigate the magnetic properties of the biopolymer microspheres and magnetite coated biopolymer including magnetite nanoparticles. Magnetic Resonance (MR) imaging was used to investigate biopolymer coated nanoparticles and biopolymer microspheres.

Preparation of Chitosan-coated Magnetite Nanoparticles (키토산이 피복된 나노 크기의 자성체 분말 제조)

  • Cho, Jun-Hee;Ko, Sang-Gil;Ahn, Yang-Kyu;Song, Ki-Chang;Choi, Eun-Jung
    • Journal of the Korean Magnetics Society
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    • v.16 no.1
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    • pp.102-106
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    • 2006
  • Magnetic nanoparticles can be used for a variety of biomedical applications. They can be used in the targeted delivery of therapeutic agents in vivo, in the hyperthermic treatment of cancers. in magnetic resonance (MR) imaging as contrast agents and in the biomagnetic separations of biomolecules. We have synthesized magnetite $(Fe_3O_4)$ nanoparticles using chemical coprecipitation technique with sodium oleate as surfactant. Nanoparticle size can be varied from 2 to 8nm by controlling the sodium oleate concentration. Magnetite phase nanoparticles could be observed from X-ray diffraction. Magnetic colloid suspensions containing particles with sodium oleate and chitosan have been prepared. Nanoparticles, both oleate-coated and chitosan-coated, have been characterized by several techniques. Atomic farce microscope (AFM) was used to image the coated nanoparticles. Magnetic hysteresis measurement were performed using a superconducting quantum interference device (SQUID) magnetometer at room temperature to investigate the magnetic properties of the magnetite nanoparticles. The SQUID measurements revealed superparamagnetism of nanoparticles.

The Crystallographic and Magnetic Properties of $Fe_{1-x}Co_x$System ($Fe_{1-x}Co_x$계의 결정구조와 자기적인 성질)

  • 김정기;한경훈;서정철
    • Journal of the Korean Magnetics Society
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    • v.9 no.4
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    • pp.190-195
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    • 1999
  • The crystallographic and magnetic properties of the system of $Fe_{1-x}Co_x$(x=0.2 and 0.4) prepared by microwave arc-melting with the maximum power of 3.5 kW and a iron-foil with thickness of 25 ${\mu}{\textrm}{m}$ have been studied by the methods of X-ray diffraction and the measurement of the magnetic hysteresis using the vibrating sample magnetometer at room temperature. The samples were prepared in three different ways: First, pellet form pressed under the pressure of 9,000 N/$\textrm{cm}^2$. Second, the sheet cold rolled. Third, thin sheet treated with the temperature of 90$0^{\circ}C$. The X-ray diffraction pattern of the sample prepared by the first method shows that the crystal structure of the sample is bcc as same as that of Fe with a good uniformity. The iron-foil has the coercivity of 43 Oe and the initial slope of magnetization of 0.328 emu/gOe. The coervicity and magnetization of the sample prepared by the second method increased as the Co content increased. But the initial slop of the magnetization decreased as the Co content increased. This means that the displacement of domain wall is suppressed by the increases of coercivity as the Co content increased. The saturation magnetization of the samples made by the third method increased. On the other hand, the coercivity of these samples decreased. The increase of saturation magnetization of the samples seems to be related to the changes in X-ray intensity after heat treatment. Also some magnetic parameters of the samples were calculated by using a simple model and compared with other values.

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Magnetic and Electric Transport Properties of MnTe Thin Film Grown by Molecular Beam Epitaxy (분자선 증착법에 의해 성장한 MnTe 박막의 자기적 및 전기수송 특성)

  • Kim, Woo-Chul;Bae, Sung-Whan;Kim, Sam-Jin;Kim, Chul-Sung;Kim, Kwang-Joo;Yoon, Jung-Bum;Jung, Myung-Hwa
    • Journal of the Korean Magnetics Society
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    • v.17 no.2
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    • pp.81-85
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    • 2007
  • MnTe layers of high crystalline quality were successfully grown on Si(100) : B and Si(111) substrates by molecular beam epitaxy (MBE). Under tellurium-rich condition and the substrate temperature around $400^{\circ}C$, a layer thickness of $700{\AA}$ could be easily obtained with the growth rate of $1.1 {\AA}/s$. We investigated the structural, magnetic and transport properties of MnTe layers by using x-ray diffraction (XRD), superconducting quantum interference device (SQUID) magnetometry, and physical properties measurement system (PPMS). Characterization of MnTe layers on Si(100) : B and Si(111) substrates by XRD revealed a hexagonal structure of polycrystals with lattice parameters, ${\alpha}=4.143{\pm}0.001{\AA}\;and\;c=6.707{\pm}0.001{\AA}$. Investigation of magnetic and transport properties of MnTe films showed anomalies unlike antiferromagnetic powder MnTe. The temperature dependence of the magnetization data taken in zero-field-tooling (ZFC) and field-cooling (FC) conditions indicates three magnetic transitions at around 21, 49, and 210 K as well as the great irreversibility between ZFC and FC magnetization in the films. These anomalies are attributable to a magnetic-elastic coupling in the films. Magnetization measurements indicate ferromagnetic behaviour with hysteresis loops at 5 and 300 K for MnTe polycrystalline film. The coercivity ($H_c$) values at 5 and 300 K are 55 and 44 Oe, respectively. In electro-transport measurements, the temperature dependence of resistivity revealed a noticeable semiconducting behaviours and showed conduction via Mott variable range hopping at low temperatures.

Sol-Gel Synthesis, Crystal Structure, Magnetic and Optical Properties in ZnCo2O3 Oxide

  • Das, Bidhu Bhusan;Barman, Bittesh
    • Journal of the Korean Chemical Society
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    • v.63 no.6
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    • pp.453-458
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    • 2019
  • Synthesis of ZnCo2O3 oxide is performed by sol-gel method via nitrate-citrate route. Powder X-ray diffraction (XRD) study shows monoclinic unit cell having lattice parameters: a = 5.721(1) Å, b = 8.073(2) Å, c = 5.670(1) Å, β = 93.221(8)°, space group P2/m and Z = 4. Average crystallite sizes determined by Scherrer equation are the range ~14-32 nm, whereas SEM micrographs show nano-micro meter size particles formed in ZnCo2O3. Endothermic peak at ~798 K in the Differential scanning calorimetric (DSC) trace without weight loss could be due to structural transformation and the endothermic peak ~1143 K with weight loss is due to reversible loss of O2 in air atmosphere. Energy Dispersive X-ray (EDX) analysis profile shows the presence of elements Zn, Co and O which indicates the purity of the sample. Magnetic measurements in the range of +12 kOe to -12 kOe at 10 K, 77 K, 120 K and at 300 K by PPMS-II Physical Property Measurement System (PPMS) shows hysteresis loops having very low values of the coercivity and retentivity which indicates the weakly ferromagnetic nature of the oxide. Observed X-band EPR isotropic lineshapes at 300 K and 77 K show positive g-shift at giso ~2.230 and giso ~2.217, respectively which is in agreement with the presence of paramagnetic site Co2+(3d7) in the oxide. DC conductivity value of 2.875 ×10-8 S/cm indicates very weakly semiconducting nature of ZnCo2O3 at 300 K. DRS absorption bands ~357 nm, ~572 nm, ~619 nm and ~654 nm are due to the d-d transitions 4T1g(4F)→2Eg(2G), 4T1g(4F)→4T1g(4P), 4T1g(4F)→4A2g(4F), 4T1g(4F)→4T2g(4F), respectively in octahedral ligand field around Co2+ ions. Direct band gap energy, Eg~ 1.5 eV in the oxide is obtained by extrapolating the linear part of the Tauc plot to the energy axis indicates fairly strong semiconducting nature of ZnCo2O3.

Magnetic Properties of Monolayer-thiciness InP(001)(2×4) Reconstruction Surface (InP(001)(2×4)재구성된 표면 위에 원자층 단위로 증착된 Co 박막의 자성 특성)

  • Park, Yong-Sung;Jeong, Jong-Ryul;Lee, Jeong-Won;Shin, Sung-Chul
    • Journal of the Korean Magnetics Society
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    • v.14 no.3
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    • pp.89-94
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    • 2004
  • We have investigated magnetic properties of monolayer (ML)-thickness Co film deposited on InP(2${\times}$4) reconstruction surface using in situ Surface Magneto-Optical Kerr Effects (SMOKE) measurement system. InP(2${\times}$4) reconstruction surface, obtained by repeated sputtering and annealing, was confirmed by reflection hish energy electron diffraction (RHEED) and scanning tunneling microscope (STM) measurements. From both longitudinal and polar SMOKE measurements, we have observed three distinguishable regions showing different magnetic properties depending on the Co thickness. In the Co film thickness smaller than 7 $m\ell$, no SMOKE signal was detected. In the following thickness between 8 $m\ell$ and 15 $m\ell$, both longitudinal and polar Kerr hysteresis loops were observed, which implies a metastable phase coexisted of in-plane and perpendicular anisotropies. In the film thickness larger than 16 $m\ell$, only longitudinal MOKE signal without polar signal was detected, which implies existence of in-plane anisotropy in this thickness region.

The Crystallographic and Magnetic Properties of $Fe_{0.8}Co_{0.18}(BN_{0.02}$ Synthesized by Heat Treatment and Plastic Deformation ($Fe_{0.8}Co_{0.18}(BN_{0.02}$의 열처리 및 소성변형에 의한 결정구조와 자기적 성질)

  • 김정기;한경훈;이상문;정재윤;김예니;신경호
    • Journal of the Korean Magnetics Society
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    • v.10 no.5
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    • pp.225-231
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    • 2000
  • The crystallographic and magnetic properties of the sample F $e_{0.8}$ $Co_{0.18}$(BN)$_{0.02}$ synthesized by microwave arc-melting with the maximum power of 3.5 kW have been studied by the methods of an X-ray diffraction and the measurement of the magnetic hysteresis using the vibrating sample magnetometer at room temperature. The samples were prepared in a form of pellet pressed under the pressure of 9,000 N/c $m^2$, rolled coldly, and treated with the different temperatures. The X-ray diffraction pattern of pelleted sample shows that the crystal structure of the sample is bcc as same as that of Fe with a good uniformity. The X-ray diffraction pattern shows that a residual stress, which exists in the sample, is eliminated by final 90$0^{\circ}C$ annealing. As rolling rate and heat treatment temperature increases, the saturation magnetization and the remanence of the samples increase whereas the coercivity of the samples shows decrease. Also the saturation magnetization and the remanence of the samples were affected by rolling rate and rolling direction than heat treatment temperature, but the coercivity of the samples was affected by rolling rate and direction as well as heat treatment temperature. This means that a domain wall motion is easy due to elimination of a residual stress and an inclusion which exists in the sample by rolling and heat treatment and a local induced-magnetization easy axis was also formed to parallel to the rolling direction due to creation of the like-atom pairs across the slip plane by rolling......

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