• Title/Summary/Keyword: Magnetic Property

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Superconducting and Magnetic Properties of the $(Ru_{1-x}Ta_x)Sr_2(Gd_{1.4}Ce_{0.6})Cu_2O_z$ System ($(Ru_{1-x}Ta_x)Sr_2(Gd_{1.4}Ce_{0.6})Cu_2O_z$ 계의 초전도 및 자기적 특성)

  • Lee, H.K.
    • Progress in Superconductivity
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    • v.13 no.3
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    • pp.163-168
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    • 2012
  • The effects of Ta substitution on the superconducting and magnetic properties of the $(Ru_{1-x}Ta_x)Sr_2(Gd_{1.4}Ce_{0.6})Cu_2O_z(0{\leq}x{\leq}0.5)$ system have been investigated. The X-ray diffraction measurements indicate that the Ta ion replaces Ru sites up to x = 0.4. It is found that the Ta substitution for Ru significantly reduces the weak-ferromagnetic component of the field-cooled magnetic susceptibility without an appreciable change of room temperature thermopower at lower Ta doping level below x = 0.2. The resistive transition temperature tends to decrease monotonically from 27 K for the x = 0 sample to 16 K (9 K) for the x = 0.4 (x = 0.5) sample. These results suggest that superconductivity of the $(Ru_{1-x}Ta_x)Sr_2(Gd_{1.4}Ce_{0.6})Cu_2O_z$ compound is not significantly affected by the magnetic state of the Ru sublattice. The experimental results are discussed in connection with previous reports on the effects of Nb substitution.

Microstructure and Magnetic properties of $Ti_{1-x}Co_xO_2$ Magnetic semiconductor thin films by Metal Organic Chemical Vapor Deposition (유기금속화학기상증착법으로 제조된 자성반도체 $Ti_{1-x}Co_xO_2$ 박막의 미세구조 및 자기적 특성)

  • Seong, Nak-Jin;Yoon, Soon-Gil
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2003.07a
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    • pp.155-159
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    • 2003
  • Polycrystalline $Ti_{1-x}Co_xO_2$ thin films on $SiO_2$ (200 nm)/Si (100) substrates were prepared using liquid-delivery metalorganic chemical vapor deposition. Microstructures and ferromagnetic properties were investigated as a function of doped Co concentration. Ferromagnetic behaviors of polycrystalline films were observed at room temperature, and the magnetic and structural properties strongly depended on the Co distribution, which varied widely with doped Co concentration. The annealed $Ti_{1-x}Co_xO_2$ thin films with $x{\leq}0.05$ showed a homogeneous structure without any clusters, and pure ferromagnetic properties of thin films are only attributed to the $Ti_{1-x}Co_xO_2$ (TCO) phases. On the other hand, in case of thin films above x=0.05, Co clusters formed in a homogeneous $Ti_{1-x}Co_xO_2$ Phase, and the overall ferromagnetic (FM) properties depended on both $FM_{TCO}$ and $FM_{Co}$. Co clusters with about 10nm-150nm size decreased the value of Mr (the remanent magnetization) and increased the saturation magnetic field.

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Microstructure Control and Magnetic Property of Nd-Fe-B Sintered Magnets After Cyclic Heat Treatment (반복 열처리한 Nd-Fe-B 소결 자석의 미세구조 제어 및 자성특성 평가)

  • Kim, Se-Hoon;Kim, Hoon-Sup;Kim, Dong-Hwan;Kim, Young-Do
    • Journal of Powder Materials
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    • v.15 no.6
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    • pp.471-476
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    • 2008
  • Sintered Nd-Fe-B magnets have been widely used due to their excellent magnetic properties, especially for driving motors of hybrid and electric vehicles. The microstructure of Nd-Fe-B magnets strongly affects their magnetic properties, in particular the coercivity. Therefore, a post-sintering process like heat-treatment is required for improving the magnetic properties of Nd-Fe-B sintered magnets. In this study, cyclic heat treatment was performed at temperatures between $350^{\circ}C$ and $450^{\circ}C$ up to 16 cycles in order to control microstructures such as size and shape of the Nd-rich phase without grain growth of the $Nd_{2}Fe_{14}B$ phase. The 2 cycles specimen at this temperature range showed more homogeneous microstructure which leads to higher coercivity of 35 kOe than as-sintered one.

Uniaxial Magnetic Anistotropy of a NiO-Spin Valve Device

  • Lee, Won-Hyung;Hwang, Do-Guwn;Lee, Sang-Suk
    • Journal of Magnetics
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    • v.14 no.1
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    • pp.18-22
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    • 2009
  • The shape anisotropy effect of a giant magnetoresistance-spin valves (GMR-SV) device with a glass/NiO/NiFe/CoFe/Cu/CoFe/NiFe layered structure for use in the detection of magnetic property of molecules within a cell was investigated. The patterned device was given uniaxial anisotropy during the sputtering deposition and vacuum post-annealing, which was performed at $200^{\circ}C$ under a 300 Oe magnetic field. The pattern size of the device, which was prepared through the photolithography process, was $2{\times}15\;{\mu}m^2$. The experimental results confirmed that the best design for a GMR-SV device to be used as a biosensor is to have both the axis sensing current and the easy axis of the pinned NiO/NiFe/CoFe triple layer oriented in the direction of the device's width, while the easy axis of the free CoFe/NiFe bilayer should be pointed along the long axis of the device.

Effect of Al on Structural and Magnetic Characteristics of CoCrFeNiMnAlx High Entropy Alloys

  • Majid Tavoosi;Ali Ghasemi;Gholam Reza Gordani;Mohammad Reza Loghman Estarki
    • Korean Journal of Materials Research
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    • v.33 no.3
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    • pp.95-100
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    • 2023
  • This research examines the effect of adding aluminum on the structural, phasic, and magnetic properties of CoCrFe NiMnAlx high-entropy alloys. To this aim, the arc-melt process was used under an argon atmosphere for preparing cast samples. The phasic, structural, and magnetic properties of the samples were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), and vibrational magnetometry (VSM) analyses. Based on the results, the addition of aluminum to the compound caused changes in the crystalline structure, from FCC solid solution in the CoCrFeNiMn sample to CoCrFeNiMnAl BBC solid solution. It was associated with changes in the magnetic property of CoCrFeNiMnAlx high-entropy alloys, from paramagnetic to ferromagnetic. The maximum saturation magnetization for the CoCrFeNiMnAl casting sample was estimated to be around 79 emu/g. Despite the phase stability of the FCC solid solution with temperature, the solid solution phase formed in the CrCrFeNiMnAl high-entropy compound was not stable, and changed into FCC solid solution with temperature elevation, causing a reduction in saturation magnetization to about 7 emu/g.

The Study on Magnetic Properties of Transition Metal Doped Semiconductor (전이금속이 치환된 반도체 물질의 자기적 특성 연구)

  • Kim, Jae-Uk;Cha, Byung-Kwan;Ji, Myoung-Jin;Kwon, Tae-Phil;Park, Byoung-Cheon;Kyoung, Dong-Hyoun;Jin, Hoon-Yeol;Kim, Seung-Hoi;Kim, Jong-Gyu
    • Journal of the Korean Chemical Society
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    • v.54 no.6
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    • pp.766-770
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    • 2010
  • This is the study of magnetic properties of transition metal doped diluted magnetic semiconductors(DMSs). The wurtzite structure samples were synthesized by the sol-gel method. The thermodynamic characteristics and magnetic properties of $Zn_{1-x}Co_xO$ single phase was investigated for different doping concentration (x = 0%, 1%, 2%, 3%, 4%, 5%, 10%, 15%). The property of diluted magnetic semiconductors has been comfirmed by X-ray diffraction (XRD), Scanning Electronic Microscope (SEM) and Vibrating sample magnetometer (VSM). The magnetic properties of pure $Zn_{1-x}Co_xO$ is found to be dominated by the ferromagnetic interaction between doped transition metal ions, where by the ferromagnetic coupling strength is simply increased with the concentration(>5%) of the doped transition metal.

The Effect of Additional Elements on the Tailored Magnetic Properties of Electrochemically Prepared CoPtP-X Alloys (전기화학적으로 제조한 CoPtP-X합금의 첨가제 효과에 따른 맞춤형 자기적 성질)

  • Park, H.D.;Lee, K.H.;Kim, G.H.;Jeung, W.Y.;Choi, D.H.;Lee, W.Y.
    • Journal of the Korean Electrochemical Society
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    • v.8 no.2
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    • pp.94-98
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    • 2005
  • Coptp films with the additive elements (X=Fe, Mn) of varying concentrations were prepared by in-situ electrodeposition, to tailor their magnetic properties. Alloys of CoPtP-X (X=Fe, Mn) were synthesized by changing the solution concentrations of Fe and Mn for electrodeposition. In the electrodeposited CoFePtP alloys, preferred orientation of the electrodeposited films changed from hexagonal (001) to (100) direction with increasing iron contents as revealed by X-ray diffraction, and these films exhibited various magnetic properties ranging from a typical hard magnetic to a soft magnetic property in accordance with microstructural variations. In the case of Mn addition, excellent hard magnetic property was observed at a specific Mn concentration of 0.0126 M in the electrolyte, with the coercivity of 4630 Oe and squareness of 0.856 and this was attributed to the fact that magnetization easy-axis (hexagonal c-axis) coincides with the preferred growth orientation of the film confirmed by transmission electron microscopy.

Magnetic Pinning Properties and Flux Jumps in Superconducting $MgB_2$

  • Yoon, W.S.;Lee, Eui-Wan;Kim, C.J.;Kim, B.G.;Ri, H.C.
    • Progress in Superconductivity
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    • v.9 no.1
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    • pp.11-17
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    • 2007
  • Magnetization studies have been carried out on $MgB_2$ polycrystalline samples in the temperature range of 5 - 44 K and in the magnetic field up to 7 Tesla. The critical current density was calculated from hysteresis loops using the Bean's critical state model, and the highest value of $J_c$ at 20 K was $2.7{\times}10^5\;A/cm^2$ at 2 Tesla. The hysteresis loops were carefully examined to determine the temperature and magnetic field range where flux jumps appeared. The first jump occurred typically at 1 Tesla. Due to the strong pinning, we observed the presence of flux jump below H = 1 Tesla at temperature below 30 K.

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Development of a Vision System for the Measurement of the Pendulum Test (진자검사 계측을 위한 영상 시스템의 개발)

  • Kim, Chul-Seung;Moon, Ki-Wook;Lee, Soo-Young;Eom, Gwang-Moon
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.56 no.4
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    • pp.817-819
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    • 2007
  • The purpose of this work is to develop a measurement system of the pendulum test with minimal restriction of experimental environment and little influence of noise. In this work, we developed a vision system without any line between markers and a camera. The system performance is little influenced by the experimental environment, if light are sufficient to recognize markers. For the validation of the system, we compared knee joint angle trajectories measured by the developed system and by the magnetic sensor system during the nominal pendulum test and the maximum speed voluntary knee joint rotation. The joint angle trajectories of the developed system during both tests matched well with those of the magnetic system. Therefore, we suggest the vision system as an alternative to the previous systems with limited practicality for the pendulum test.

Effect of Carrier Gas on the Microstructure and Magnetic Properties of Co Nanoparticles Synthesized by Chemical Vapor Condensation (화학기상응축공정(Chemical Vapor Condensation)으로 제조된 Co 나노분말의 미세구조 및 자기적 성질에 미치는 운송기체의 영향)

  • ;X. L. Dong
    • Journal of Powder Materials
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    • v.11 no.1
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    • pp.16-21
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    • 2004
  • The nano-sized Co particles were successfully synthesized by chemical vapor condensation (CVC) process using the precursor of cobalt carbonyl ($Co_2(CO)_8$). The influence of carrier gases on the microstructure and magnetic properties of nanoparticles was investigated by means of XRD, TEM, XPS and VSM. The Co nano-particles with different phases and shapes were synthesized with a change of carrier gas : long string morphologies with coexistence of fcc and hcp structure in Ar carrier gas condition; finer Co core in a mass of cobalt oxide with only fcc structure in He; rod type cobalt oxide phase in Ar+6vol%$O_2$. The saturation magnetization and coercivity was lower in Co nanoparticles synthesized in He carrier gas, due to their finer size.