• 제목/요약/키워드: spin wave

검색결과 214건 처리시간 0.025초

Revival of Phonons in High Tc Superconductors

  • Bang, Yun-Kyu
    • Progress in Superconductivity
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    • 제9권2호
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    • pp.127-135
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    • 2008
  • We study the effects of phonon interaction on the superconducting pairing in the high $T_c$ superconductors (HTSC). Using coupled BCS gap equations, we found that phonon interaction can induce a s-wave component to the d-wave gap, mediated by Antiferromagnetic (AFM) spin fluctuations, in the (D+iS) form. However, $T_c$ is not enhanced compared to the pure d-wave pairing without phonon interaction. On the other hand, anisotropic phonon interaction can dramatically enhance the d-wave pairing and $T_c$ itself, together with the AFM spin fluctuation interaction. This ($D_{AFM}+D_{ph}$) type pairing exhibits strongly reduced isotope coefficient despite the large enhancement of $T_c$ by phonon interaction.

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On wave propagation of football ball in the free kick and the factors affecting it

  • Xumao Cheng;Ying Wu
    • Steel and Composite Structures
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    • 제46권5호
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    • pp.669-672
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    • 2023
  • In this research, the researcher has examined the factors affecting the movement of the soccer ball and will show that the effects such as air resistance, altitude above sea level, wind, air pressure, air temperature, air humidity, rotation of the earth, changes in the earth's gravitational acceleration in different areas. It, the geographical length and latitude of the launch point, the change of gravitational acceleration with height, the change of pressure with height, the change of temperature with height and also the initial spin (Magnus effect) affect the movement of projectiles (especially soccer ball). We modelled th ball based on shell element and derive the motion equations by energy method. Finally, using numerical solution, the wave of the ball is studied. The influences of various parameters are investigated on wave propagation of the ball. Therefore, in short, it can be said that the main factors that play a major role in the lateral deviation of the hit ball are the initial spin of the ball and the wind.

비정질 Fe-Co-Re-B(RE=Nd, Sm, Gd, Tb) 합금의 자기적 성질 (A Study on the Magnetic Properties of Amorphous Fe-Co-RE-B (RE=Nd, Sm, Gd, Tb) Alloys)

  • 김경섭;유성초;김창식;김종오
    • 한국자기학회지
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    • 제1권2호
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    • pp.55-59
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    • 1991
  • 희토류-3d 천이원소인 비정질${[{(Fe_{80}CO_{20})}_{0.98}RE_{0.02}]}_{80}B_{20}(RE=Nd,\;Sm,\;Gd,\;Tb)$ 합금 리본시료에 대한 자기적 성질을 조사하기 위하여 시료진동형 자력계(vibrating sample magnetometor)를 이용하여 77 K부터 900 K까지의 온도 영역에서 포화자화 값을 온도의 함수로 측정 한후, Curie 온도 ($T_{c}$)와 Bloch 상수등을 추정하였다. 이들로 부터 spin wave stiffness 상수, 교환상호작용(exchange interaction)의 범위와 평균자승거리($$)등을 계산하였으며 각 희토류 원소에 대한 치환효과를 비교 분석하였다.

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Spin injection and transport properties of Co/Au/Y$Ba_2$$Cu_3$$O_y$ tunnel junctions

  • Lee, Kiejin;Kim, Sunmi;Ishibashi, Takauki;Cha, Deokjoon
    • Progress in Superconductivity
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    • 제3권1호
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    • pp.70-73
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    • 2001
  • We report the spin injection and transport properties of three terminal devices of Co/Au/$YBa_2$$Cu_3$$O_{y}$(F/N/S) tunnel junctions by injection of spin-polarized quaiparticles using a cobalt ferromagnetic injector. The observed current gain depends on the thickness of Au interlayer and is directly related to the nonequilibrium magnetization due to spin relaxation effects. The tunnel characteristic of a F/N/S tunnel junctions exhibited a zero bias conductance peak (ZBCP). The suppression of the ZBCP was observed due to the suppression of Andreev reflection at the interface, which is due to the spin scattering processes at the interface between a ferromagnetic and a d-wave superconductor.r.

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리간드의 Spin-Orbit Coupling이 작은 스핀팔면체 Ti(Ⅲ), V(Ⅲ), Fe(Ⅲ) 및 Ni(Ⅱ) 착물의 Zero-Field Splitting에 미치는 영향 (The Effect of the Ligand's Spin-Orbit Coupling on the Zero-Field Splitting in the Low Spin Octahedral Ti(Ⅲ), V(Ⅲ), Fe(Ⅲ) and Ni(Ⅱ) Complexes)

  • 안상운;이기학
    • 대한화학회지
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    • 제23권2호
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    • pp.65-74
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    • 1979
  • 팔면체$ [Ti(Ⅲ)A_3B_3]$, $ [V(Ⅲ)A_3B_3]$, $ [Fe(Ⅲ)A_3B_3]$$ [Ni(Ⅱ)A_3B_3]$ 형태 착물의 바닥상태에 대한 리간드 궤도함수의 spin-orbit coupling의 영향을 고찰하여 보았다. 리간드 궤도함수의 spin-orbit coupling이 바닥상태의 파동함수에는 영향을 주지 않았으나 에너지 준위의 분열에는 영향을 주었으며, 그 크기는 Ti(Ⅲ) > V(Ⅲ) > Fe(Ⅲ)의 순서로 감소하였다

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SWR as Tool for Determination of the Surface Magnetic Anisotropy Energy Constant

  • Maksymowicz, L.J.;Lubecka, M.;Jablonski, R.
    • Journal of Magnetics
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    • 제3권4호
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    • pp.105-111
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    • 1998
  • The low energy excitations of spin waves (SWR) in thin films can be used for determination of the surface anisotropy constant and the nonhomogeneities of magnetization in the close-to-surface layer. The dispersion relation in SWR is sensitive on the geometry of experiment. We report on temperature dependence of surface magnetic anisotropy energy constant in magnetic semiconductor thin films of$ CdCr_{2-2x}In_{2x}Se_4$ at spin glass state. Samples were deposited by rf sputtering technique on Corning glass substrate in controlled temperature conditions. Coexistence of the infinite ferromagnetic network (IFN) and finite spin slusters (FSC) in spin glass state (SG) is know phenomena. Some behavior typical for long range magnetic ordering is expected in samples at SG state. The spin wave resonance experiment (microwave spectrometer at X-band) with excited surface modes was applied to describe the energy state of surface spins. We determined the surface magnetic anisotropy energy constant versus temperature using the surface inhomogeneities model of magnetic thin films. It was found that two components contribute to the surface magnetic anisotropy energy. One originates from the exchange interaction term due to the lack of translation symmetry for surface spin as well as from the originates from the exchange interaction term due to the lack of translation symmetry for surface spin as well as from the stray field of the surface roughness. The second one comes from the demagnetizing field of close-to surface layer with grad M. Both term linearly decrease when temperature is increased from 5 to 123 K, but dominant contribution is from the first component.

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