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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Journal of Magnetics
Journal Basic Information
Journal DOI :
The Korean Magnetics Society
Editor in Chief :
Sang Ho Lim
Volume & Issues
Volume 4, Issue 4 - Dec 1999
Volume 4, Issue 3 - Sep 1999
Volume 4, Issue 2 - Jun 1999
Volume 4, Issue 1 - Mar 1999
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Magnetic Characterization of the Nd Based Permanent Magnet by Newly-Developed Bipolar Pulse-Type Hysteresis Loop Tracer
Rhee, J.R. ;
Journal of Magnetics, volume 4, issue 3, 1999, Pages 73~75
By appliying an slternate pulsed magnetic field -generated by using a sequential ignition circuit and a magnet exciting circuit- with peak value of about 10 T to the rod type Nd based magnet Nd2Fe12.7Cr1.3B with length of 5 mm and diameter of 3.6 mm, the basic magnetic properties such as saturation magnetization, residual magnetization, coercivity, maximum energy products, magnetic anisotropy and anisotropic field are investigated with obtaining the major and minor J-H loops of the magnet. The increase in coercivity due to eddy currents in ac measurement of coercivity is calculated considering eddy current loss by analyzing a wave of generating magnetic field. The average coercivity calculated for the magnet is about 12.2 kOe, anisotropy magnetic field and anisotropic constant are measured as 60 kOe 2.43 Mj/
Glassy Dynamics in Giant Magnetoresistive Melt-spun Co-Cu
Idzikowski, B. ; RoBler, U.K. ; Handstein, A. ; Eckert, D. ; Wolf, M. ; Nenkov, K. ; Muller, K.H. ;
Journal of Magnetics, volume 4, issue 3, 1999, Pages 76~79
We report results on metastable CuCo ribbons at low Co contents (2 and 10 at %), which were prepared by conventional melt-spinning technique and subsequent annealing. The properties of these materials cannot consistently be described by those of an assembly of superparamagnetic single-domain particles. Magnetic measurements related to magnetic dynamics reveal spin-glass-like properties. Especially, we find very slow nonequilibrium relaxation processes in Co10Cu90, which depend on prehistory, when probing the relaxation of the resistivity. The results are clear evidence for frustrated interaction effects due to magnetic couplings between Co clusters or precipitates in these alloys.
The Role of Superparamagnetic Particle Size Distribution and Ferromagnetic Phase on GMR in Granular Cu-Co Alloys
Kumiski, M ; Waniewska, A.Slawska ; Lachowicz, H.K ;
Journal of Magnetics, volume 4, issue 3, 1999, Pages 80~83
Relations between giant magnetoresistance (GMR) characteristic, magnetic properties and structure were investigated in Cu90Co10 alloy obtained by melt spinning in which GMR was enhanced by appropriate annealing. The structure of the annealed sample is not homogeneous (though the sizes distribution of the majority of Co-particles is not very wide but much larger particles are also present). On the other hand, the GMR characteristics differs from that expected theoretically for identical superparamagnetic particles. It is shown that ther main sources of the observed non-quadratic magnetoresistance dependence on magnetization are differentialted surface to volume ratio of superparamagnetic particles and the ferromagnetic phase contribution to the total magnetization which was calculated applying the new method.
Magnetization Processes in Partially Crystallized Co-Based Metallic Glass
Lachowicz, H.K. ; Poplawsi, F. ; Zuberek, R. ; Kuzminski, M. ; Slawska-Waniewska, A. ; Dynowska, E. ; Yu, S.C. ;
Journal of Magnetics, volume 4, issue 3, 1999, Pages 84~87
It is shown that progressive crystallization of non-magnetostrictive Co-based metallic glass (VITROVAC 6030) leads to an increase of coercivity by more than three orders of magnitude. The mechani는 responsible for this phenomenon are interpreted showing that the main source for the giant increase of the coercivity is the pinning effect on the domain walls originating from the created crystallites of the size much smaller than the domain width (correlation length for ferromagnetic exchange interactions). It is also shown that gradually devitrified non-magnetostrictive metallic glass is an excellent model material for verification of N el's theory describing the Rayleigh rule.
Effect of Columnar Structures on Exchange Anisotropy Field in Magnetoresistive NiO/NiFe Bilayers
Jai-Young Kim ; Gyeong-Su Park ; Jae-Chul Ro ; Su-Jeong Suh ;
Journal of Magnetics, volume 4, issue 3, 1999, Pages 88~91
A series of NiO/NiFe bilayer films are deposited with the variation of Ar sputtering pressure for the NiO layers only. As the pressure for the NiO layers increases, the exchange anisotropy field (HEX) decreases gradually and becomes extinct at 2.5 mTorr, at which the maximum coercive force (HC) in the NiO/NiFe films is obtained. Randomly oriented columnar structures with HEX a few tens of Oe and oriented columnar structures with zero HEX are observed in the NiP layers by highvoltage hihg-resolution transmission electron microscopy. The vanishing of the HEX in the oriented structures is attributed to the lack of exchange anisotropy energy (EEX) between NiO and NiFe layers, which results in little contribution of interfacial unidirectional pinning anisotropy to the interface of NiO/NiFe bilayer.
Ferromagnetic Resonance Studies of Ultrathin Co Layers in Co/Ag Multilayers
Dubowik, J. ;
Journal of Magnetics, volume 4, issue 3, 1999, Pages 92~97
A relationship between microstructure and ferromagnetic resonance of Co/Ag multilayers has been studied in as-deposited and annealed multilayers iwth ultrathin (dCo < 1 nm) Co layers. Depending on the nominal thickness of Co Co/Ag multilayers represent a system of fine magnetic particles (dCo < 0.4 nm) or discontionuous layered structure (dCo/0.5 nm). FMR data has been interpreted in the framework of a odel of interacting fine particles exhibiting superparamagnetic behavior. Changes in the FMR spectra upon annealing have been attributed to the growth of the Co particles and to a transition from the fcc to hcp atomic structure of the highly (111) textured Co particles.
Under Water Sonar Transducer Using Terfenol-D Magnetostrictive Material
Son, Derac ; Cho, Yuk ;
Journal of Magnetics, volume 4, issue 3, 1999, Pages 98~101
In this work we htave constructed an under water sonar transducer using Terfenol-D rod employing open magnetic circuit. Normally Sonar transducer using Terfenol-D was designed under closed magnetic flux return path, and permanent magnet for dc bias marnetic field, but high magnetic field should be applied to the transducer coil for high sound power and it brings temperature increase inside of the transducer. To improve this heat dissipation problem, we have designed an open magnetic circuit type transducer and we can get 200 dB (re. 1 Pa @ 1m) sound power for the input power of 650 VA.
Intermediate Valence State of Cerium in Intermetallics
Suski, Wojciech ;
Journal of Magnetics, volume 4, issue 3, 1999, Pages 102~106
Ce exhibits the intermediate valence (IV) state both as an element and in its compounds. In the present review characteristic behavior of the materials showing the IV state are described. Then the methods of producing this state : the application of the external pressure, temperature and magnetic field as well as the alloying are being discussed. An identification of the IV state is frequently not a simple goal and the best results can be obtained using a combination of various independent methods. Particular attention is paid to the X-ray spectroscopy, lattice parameters and the magnetic properties. As the examples of the IV state in the Ce compounds the properties of following materials are reported : CeRhSb,
and for comparison Sc1-xYbxFe4Al8.