• Title/Summary/Keyword: inelastic neutron scattering

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Low Temperature Magnetization and Spin Wave Excitations in Amorphous Fe67 Co18B14Si1

  • Yoo, Yong-Goo;Yu, Seong-Cho;Hans A. Graf
    • Journal of Magnetics
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    • v.2 no.3
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    • pp.72-75
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    • 1997
  • The temperature dependent saturation magnetization curve of amorphous Fe67 Co18B14Si1, alloy was measured using a SQUID magnetometer and vibrating sample magnetometer from 5 K up to 800 K. Inelastic neutron neutron scattering measurements also have been used to study the long wavelength spin dynamics of this high Tc amorphous ferromagnetic alloy. The magnon dispersion curve exhibit the conventional quadratic relationship E = D (T) q2 + $\Delta$, typical of an iso=obtained from a low temperature magnetization curve, which was consistent with the value obtained from the analysis oif inelastic neutron scattering data after consideration of its temperature dependence.

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Analysis of the Magnetic Properties of RFe11Ti and RFe11TiH (R=Tb,Ho)

  • Xu, S.W.;Yan, Y.;Jin, H.M.;Wang, X.F.;Wang, W.Q.;Su, F.
    • Journal of Magnetics
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    • v.8 no.4
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    • pp.153-156
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    • 2003
  • The values of crystalline-electric-field parameters $A_{nm}$ for $RFe_{11}$Ti $H_{x}$ (R=Tb,Ho) (x=0,l) are obtained by fitting calculations to the magnetization curves along the crystal axes at 4.2 K and higher temperatures. The insertion of H element in RFe$_{11}$Ti significantly affects CEF parameters $A_{nm}$ . By using exchange field 2${\mu}$$_{B}$ $H_{ex}$ derived by inelastic neutron scattering and fitted $A_{nm}$ , the calculations reproduce the experimental curves well.

Eliashberg Calculation of the Momentum-Resolved Self-Energy for the Cuprate Superconductors Induced by the Spin Fluctuations (구리 산화물 계열 초전도체에서의 스핀 요동에 의한 자체 에너지의 엘리아시버그 계산)

  • Hong, Seung-Hwan;Choi, Han-Yong
    • Progress in Superconductivity
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    • v.13 no.3
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    • pp.146-150
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    • 2012
  • We solve the momentum resolved d-wave Eliashberg equation employing the magnetic excitation spectrum from the inelastic neutron scattering on the LSCO superconductors reported by Vignolle et al. The magnetic excitation spectrum exhibits 2 peaks: a sharp incommensurate peak at 18 meV at momentum (${\pi}$, ${\pi}{\pm}{\delta}$) and (${\pi}{\pm}{\delta}$, ${\pi}$) and another broad peak near 40~70 meV at momentum (${\pi}$, ${\pi}$). Above 70 meV, the magnetic excitation spectrum has a long tail that is shaped into a circle centered at (${\pi}$, ${\pi}$) with ${\delta}$. The sign of the real part of the self-energy is determined by the momentum position of the peaks of the magnetic excitation spectrum and bare dispersion. We will discuss the effects of the each component of the magnetic excitation spectrum on the self-energy, the pairing self-energy.

Introduction to Neutron Scattering for Magnetic Materials Research (자성소재 연구를 위한 중성자산란 입문)

  • Jeong, Jae-Hong;Lee, Sang-Hyun;Park, Je-Geun
    • Journal of the Korean Magnetics Society
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    • v.22 no.3
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    • pp.103-108
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    • 2012
  • Having a de Broglie wavelength of a few ${\AA}$ with its corresponding energies in the range of a few to a few hundreds meV, neutrons are ideally suited for the studies of structure and dynamics in condensed matter research. Neutron scattering has been developed over the past 60 years or so and become a very mature and established experimental technique in the very broad range of material sciences. In this short introductory article, we have explained its working principles and provided few selected examples of application.

An Analysis of Inelastic Neutron Scattering by Liquid Methane

  • Chung, Chang-Hyun;Shin, Won-Kee;Kim, Jin-Soo
    • Nuclear Engineering and Technology
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    • v.5 no.4
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    • pp.265-278
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    • 1973
  • The incoherent neutron scattering cross section of molecular liquids is analyzed using a damping function model for correlation functions of molecular translations and rotations. The present approach is different from recent works in that the scattering function is evaluated directly, not through the intermediate scattering function. The damping fuction is determined from a simple relation between its long-wavelength limit and the generalized frequency distribution function, and translation-rotation couplings are assumed to be neglected. A physical model is used for the translational motions of center-of-mass of a molecule, including properly its short-time and long-time behaviors. A simple model for the rotational motions is suggested which relates the damping function to the Fourier transform of the dipole correlation function, or equivalently, the infrared vibrational absorption spectrum. Theoretical absolute scattering intensities are computed for liquid methane and shown to be in satisfactory agreement with both thermal and cold neutron measurements.

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New Magnetic Phases of Fe-N and Mn-Al Alloys Produced by Mechanochemical Milling (기계적 밀링 및 화학적 추출법에 의해 제조한 Fe-N 및 Mn-Al계의 새로운 자성재료)

  • Kyu-Jin Kim;Tae-Hwan Noh;Kenji Suzuki
    • Journal of the Korean Magnetics Society
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    • v.4 no.4
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    • pp.347-354
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    • 1994
  • The structural change and magnetic properties of mechanically milled Fe-N and Mn-Al alloy powders have been investigated by XRD, TEM, VSM, $M\"{o}ssbauer$ spectroscopy and inelastic neutron scattering measurements. During milling of ${\gamma}'-Fe_{4}N$ powders, and fcc ${\gamma}'-Fe_{4}N$ phase is transformed to a bct ${\alpha}'-Fe(N)$ phase by stress-induced martensitic transformation, being accompanied by an initial increase in saturation magnetization. During annealing the bct ${\alpha}'-Fe(N)$ nanocrystalline phase which is obtained by mechanical grinding for a long time, an ${\alpha}'-Fe_{16}N_{2}$ phase partially appears as an intermediate phase at 673~773 K, causing an increase in saturation magnetization. During milling of Mn-45, 70 and 85 at.% Al mixed powders, Al atoms are partially solubilized into an ${\alpha}-Mn$ phase. The Al supersaturated ${\alpha}-Mn-type$ phases change from paramagnetic to ferromagnetic : the saturation magnetization is 11 emu/g for the as-milled Mn-70 at.% Al powders. Moreover, by removing almost all Al atoms from the as-milled Mn-85 at.% Al powders using chemical leaching, the saturation magnetization increases up to 36 emu/g. The above bct ${\alpha}'-Fe(N)$ and ferromagnetic ${\alpha}-Mn$ type alloys are the magnetic materials found for the first time, by using the present mechanochemical process.

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