• 제목/요약/키워드: spin wave

검색결과 213건 처리시간 0.037초

철 초전도체에서 스핀 밀도 파와 $\pi$ 위상 차 초전도성의 상전이 그림 (Phase Diagram of Spin Density Wave and $\pi$ Phase Shifted Superconductivity in the Fe Pnictide Superconductors)

  • 이나영;최한용
    • Progress in Superconductivity
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    • 제11권2호
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    • pp.112-117
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    • 2010

  • We examine phase transition of the spin density wave and $\pi$ phase shifted superconductivity in the Fe pnictide superconductors. The phase diagram is described in the plane of the temperature T and the doping x with the combination of Ginzburg-Landau expansion of the free energy near the multi-critical temperature $T_c$ and the self-consistent numerical iterations of the gap equations. The phase separation or coexistence is determined by computing the 4-th order terms of the free energy which is confirmed by the numerical calculations. We can show the phase coexistence when the spin density wave is incommensurate. And the first order phase transition is observed near the boundary between commensurate and incommensurate spin density wave.

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Micromagnetic simulations based on directly observed microstructures

  • Lee, Je-Hyun;Kim, Sang-Koog
    • 한국자기학회:학술대회 개요집
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    • 한국자기학회 2011년도 자성 및 자성재료 국제학술대회
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    • pp.9-10
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    • 2011

  • We have prepared FePtCu L10 bit patterned media, of which magnetic properties and microstructural details are obtained by direct measurement and observations. The patterning process on the continuous film induced a drastic changes in the coercivity, SFD, and angular dependencies. The origin of the changes are explained by micromagnetic simulations with the finite element models including the details of the microstructures.

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Dynamics of Transverse Magnetic Domain Walls in Rectangular-shape Thin-film Nanowires Studied by Micromagnetic Simulations

  • Lee, Jun-Young;Choi, Sang-Kook;Kim, Sang-Koog
    • Journal of Magnetics
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    • 제11권2호
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    • pp.74-76
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    • 2006

  • Dynamic behaviors of transverse domain walls (TDWs) in rectangular shaped thin-film magnetic nanowires with different widths under applied magnetic fields less than the Walker field were studied by micromagnetic simulations. It was found that the velocity of stable TDWs in the viscous region increases from 147 to 419 m/s and their mass decreases from $6.24{\times}10^{-23}\;to\;2.70{\times}10^{-23}kg$ with increasing strength of the applied magnetic field ranging from 5 to 20 Oe for the nanowire with a dimension of 10 nm in thickness and $5{\mu}m$ in length, and 50 nm in width. With increasing the width of nanowires from 50 to 125 nm at a specific field strength of 5 Oe, the TDW's velocity also increases from 147 to 246 m/s and its mass decreases from $6.24{\times}10^{-23}\;to\;5.91{\times}10^{-23}kg$.

  • https://doi.org/10.4283/JMAG.2006.11.2.074 인용 PDF KSCI

Magnetic-vortex Dynamic Quasi-crystal Formation in Soft Magnetic Nano-disks

  • Kim, Junhoe;Kim, Sang-Koog
    • Journal of Magnetics
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    • 제22권1호
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    • pp.29-33
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    • 2017

  • We report a micromagnetic numerical study on different quasi-crystal formations of magnetic vortices in a rich variety of dynamic transient states in soft magnetic nano-disks. Only the application of spin-polarized dc currents to a single magnetic vortex leads to the formation of topological-soliton quasi-crystals composed of different configurations of skyrmions with positive and negative half-integer numbers (magnetic vortices and antivortices). Such topological object formations in soft magnets, not only in the absence of Dzyaloshinskii-Moriya interaction but also without magnetocrystalline anisotropy, are discussed in terms of two different topological charges, the winding number and the skyrmion number. This work offers an insight into the dynamic topological-spin-texture quasi-crystal formations in soft magnets.

  • https://doi.org/10.4283/JMAG.2017.22.1.029 인용 PDF KSCI