• Title/Summary/Keyword: amorphous Fe

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Magnetoresistance Characteristics of Magnetic Tunnel Junctions Consisting of Amorphous CoNbZr Alloys for Under and Capping Layers

  • Chun, Byong Sun;Lee, Seong-Rae;Kim, Young Keun
    • Journal of Magnetics
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    • v.9 no.1
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    • pp.13-16
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    • 2004
  • Magnetic tunnel junctions (MTJs) comprising amorphous CoNbZr layers have been investigated. $Co_{85.5}Nb_8Zr_{6.5}$(in at. %) layers were employed to substitute the traditionally used Ta layers with an emphasis given on under-standing underlayer effect. The typical junction structure was $SiO_2/CoNbZr$ or Ta 2/CoFe 8/IrMn 7.5/CoFe 3/Al 1.6 + oxidation/CoFe 3/CoNbZr or Ta 2 (nm). For both as-deposited state and after annealing, the CoNbZr-underlayered structure showed superior surface smoothness up to the tunnel barrier than Ta-underlayerd one (rms roughness of 0.16 vs. 0.34 nm). CoNbZr-based MTJs was proven beneficial for increasing thermal stability and increasing $V_h$ (the bias voltage where MR ratio becomes half) characteristics than Ta-based MTJs. This is because the CoNbZr-based junctions offer smoother interface structure than the Ta-based one.

The Magnetic and Magnetostrictive Properties of Melt-Spun Ribbons of B Containing Terfenol-D Alloys

  • Kim, S. R.;S. Y. Kang;S. H. Lim
    • Journal of Magnetics
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    • v.2 no.1
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    • pp.1-6
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    • 1997
  • The magnetic and magnetostrictive properties of melt-spun ribbons of the alloys (R0.33Fe0.67)1-xBx (R=Tb0.3Dy0.7 and 0$\leq$x$\leq$0.06) are ivestigated as a function of wheel speed during melt-quenching. The saturation magnetiation of the alloys with a crystalline phase ranges from 70 to 80 emu/g and does not vary substantially with the B content. The saturation magnetization of an amorphous phase, which is formed at the condition of thigh wheel speed and high B content, is reduced significantly, however. The coercive force is minimum at x= 0.02 and increases monotonously with the further increase of B content when the microstructure mainly consists of a crystalline phase, but again it is reduced significantly by the formation of an amorphous phase. The low field sensitivity of magnetostriction with magnetic field is found to be good for the alloys with x$\leq$0.04 over a wide range of wheel speed. This magnetostrictive behavior is in contrast with that observed previously for Dy-Fe and Tb-Fe based alloys and is thought to be due to low intrinsic magnetocrystalline anisotropy of the compound.

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A Study of Magnetic Properties in $Fe_{73.9}Cu_{1.0}Nb_{3.5}Si_{14.0}B_{7.6}$ by Magnetic Annelaing

  • Kim, Eng-Chan;Kim, Jin-Eui;Nam, Hyo-Duk
    • Transactions on Electrical and Electronic Materials
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    • v.1 no.3
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    • pp.29-33
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    • 2000
  • The crystallographic and high frequency characteristics of $Fe_{73.9}Cu_{1.0}Nb_{3.5}Si_{14.0}B_{7.6}$ soft magnetic alloys were investigated under magnetic field annealing, The crystallization fraction of annealed samples with longitudinal magnetic fields is higher than that of samples without magnetic field. When the transverse magnetic field is applied, the crystallization fraction does not increases but decreases until $500^{circ}C$. It is found that for samples, the saturation induction are all same with 1.3 T. The coercive field of as-cast samples is 1.03 A/cm, but in annealed samples it decrease from 0.56 to 0.1A/cm with increasing annealing temperature from 400 to $550^{circ}C$. The squareness of annealed samples under transverse magnetic field has a small value than that of both without field and with longitudinal field annealing. It is noted that the magnetic field annealing with transverse direction to amorphous $Fe_{73.9}Cu_{1.0}Nb_{3.5}Si_{14.0}B_{7.6}$ profoundly influenced on the Mossbauer spectra in contrast to that with longitudinal direction and without magnetic field.

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The Effect of Deuterium Injection to Amorphous $Fe_{90}Zr_{10}$ (비정질 $Fe_{90}Zr_{10}$의 중수소 주입효과)

  • Park, C.M.;Kang, S.K.;Lee, K.B.;Kim, C.K.;Nahm, K.;Chang, K.H.;Kim, Y.B.;Kim, C.S.
    • Journal of the Korean Magnetics Society
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    • v.2 no.1
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    • pp.1-7
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    • 1992
  • Deuterium was injected into melt-spun ribbons of ${\alpha}-Fe_{90}Zr_{10}$ using the electrolytic hydrogenation method, and the magnetic properties of these ${\alpha}-D_{x}Fe_{90}Zr_{10}$ ribbons were studied. By comparing these results with those of ${\alpha}-H_{x}Fe_{91}Zr_{9}$, the effects of phonons to magnetic properties were investigated. The Curie temperature $T_{c}$, and the spontaneous magnetizations of the $D_{47}Fe_{90}Zr_{10}$ and the $Fe_{90}Zr_{10}$ were studied using the Mbssbauer spectroscopy. From these investigations, it was found that the Curie temperature of $D_{x}Fe_{90}Zr_{10}$ was 75K higher than that of $Fe_{90}Zr_{10}$. It was believed that this indicated the importance of local deformation to the amorphous magnetism. Also by comparing the spontaneous magnetizations of $D_{47}Fe_{90}Zr_{10}$ with those of $Fe_{90}Zr_{10}$ as a function of temperature, it was found that the deuterium injection reduced the fluctuation of exchange integral.

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A study on the fabrication process development of FeTi type alloy for Ni/MH battery (니켈-수소 2차전지용 철-티타늄계 전극용 합금제조 공정에 관한 연구)

  • Lee, Moon-Goo;Kim, Eul-Su;Jeong, Sun-Dol;Kim, Ki-Won;Ahn, Hyo-Jun
    • Journal of Hydrogen and New Energy
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    • v.10 no.1
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    • pp.1-7
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    • 1999
  • In order to study on the effect of fabrication methods on the changes of hydrogenation properties of FeTi alloy, FeTi samples were prepared using three different methods, i.e., arc melting, mechanical alloying and combination of the two methods. The FeTi prepared by mechanical alloying represented amorphous structure. The hydrogen storage capacity of arc melted FeTi alloy is larger than any other samples. However, FeTi electrode fabricated by mechanical alloying after arc melting showed largest discharge capacity among them.

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