http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Contribution of Convex Surfaces to Magnetostatic Interaction in Granular Medium
Jehyun Lee,Suess, D.,Schrefl, T.,Eu Sun Yu,You Sub Lee,Kyu Hwan Oh,Fidler, J. IEEE 2009 IEEE transactions on magnetics Vol.45 No.6
<P>Finite element micromagnetic studies on the magnetic behaviors of granular structures are performed to investigate the magnetostatic contributions of the curved surfaces of grains with various film thicknesses. From the result, it is found that the magnetization reversal process in one grain is much faster when the grains have convex surfaces. The magnetization vectors of all convex models are stabilized in shorter time by factor of 10 compared to those of flat models. And, the reversals of each grain are carried out by nucleation and domain wall propagation in the entire granular structure, whereas the grains in flat model are individually reversed. Moreover, the magnetization behaviors of the convex models are closer to the experimental results. Since the geometric and magnetic conditions are same for the two models, the only origin of the more realistic magnetic behavior is the magnetostatic interaction between the grains, enhanced by introducing the convex surfaces. From the further analysis, it is found that the convex surface induces pinning field that suppress other parts' reversal.</P>
Neu, V,Schulze, C,Faustini, M,Lee, J,Makarov, D,Suess, D,Kim, S-K,Grosso, D,Schultz, L,Albrecht, M IOP Pub 2013 Nanotechnology Vol.24 No.14
<P>Magnetization reversal processes in Co/Pt multilayers prepared on nanoperforated templates are probed by magnetization relaxation measurements. The signature of pinning controlled domain wall movement as expected for percolated media is identified. This contrasts with the nucleation-type reversal mechanism of a Co/Pt reference film prepared on a smooth substrate. A zero field energy barrier of 93<I>k</I><SUB>B</SUB><I>T</I> is determined by fluctuation field measurements and is elucidated by micromagnetic calculations using the nudged elastic band method. This value is sufficiently large to qualify the material as a promising percolated medium.</P>
Stabilization and dynamical switching of skyrmions and skyrmioniums in magnetic hemispherical shells
Jaehak Yang,Hyeon-Kyu Park,Gyuyoung Park,Claas Abert,Dieter Suess,Sang-Koog Kim 한국자기학회 2021 한국자기학회 학술연구발표회 논문개요집 Vol.31 No.2
We explored the topological magnetic textures of vortices, skyrmions, and skyrmioniums in magnetic hemispherical shells by varying surface-normal uniaxial magnetic anisotropy constant (Ku), Dzyaloshinskii-Moriya interaction (DMI) constant (Dint), and the shell diameter 2R. For given values of 2R, the combination of Ku and Dint plays a crucial role in the stabilization of those different spin textures. With decreasing 2R, the geometrical confinement of hemispherical shells more significantly affects the stabilization of skyrmions owing to curvature-induced DM-like interaction. This effect is contrastingly dependent on the sign of Dint: skyrmion formation is more favorable for positive Dint values, whereas it is less favorable for negative ones. A quite promising feature is that skyrmions can be stabilized even in the absence of intrinsic DMI for 2R < 25 nm. We also explored characteristic dynamic properties of skyrmions excited by in-plane and out-of plane oscillating magnetic fields. Similar to the fundamental dynamic modes found in planar dots, in-plane gyration and azimuthal spin-wave modes as well as out-of-plane breathing modes were found, but additional higher-frequency hybrid modes also appeared due to coupling between radially quantized and azimuthal spin-wave modes. Finally, we found a switching behavior of skyrmion polarity through a transient skyrmionium state using very-low-strength AC magnetic fields. This work provides further physical insight into the static and dynamic properties of skyrmions in curved-geometry nanodots and suggests potential applications to low-power consumption and ultra-high-density information-storage devices.