Skyrmions是穩(wěn)定拓?fù)滟|(zhì)地，具有與粒子相似的性質(zhì),，它是一個(gè)最初用來(lái)描述核粒子的數(shù)學(xué)概念,，但過(guò)去十年卻在從微觀到宇宙的所有尺度上都得到了應(yīng)用。
事實(shí)證明,，Skyrmions對(duì)于描述磁體中新穎的自旋構(gòu)形尤為有用,，而且去年Skyrmions在磁性化合物MnSi 和 Fe1-xCoxSi中的存在也通過(guò)中子散射實(shí)驗(yàn)得到證實(shí)。
現(xiàn)在,，Yu等人利用透射電子顯微鏡獲得了后一種化合物的一個(gè)二維skyrmion晶格的真實(shí)空間圖像,，其形式為渦旋自旋結(jié)構(gòu)的一個(gè)六邊形排列。
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該晶格被發(fā)現(xiàn)在一系列不同溫度和磁場(chǎng)下都是非常穩(wěn)定的,。本文作者們猜測(cè),，所觀測(cè)到的納米尺度的自旋拓?fù)湟苍S會(huì)導(dǎo)致有趣的、新的電磁效應(yīng)的發(fā)現(xiàn),。(生物谷Bioon.net)
生物谷推薦原文出處：
Nature doi:10.1038/nature09124
Real-space observation of a two-dimensional skyrmion crystal
X. Z. Yu, Y. Onose, N. Kanazawa, J. H. Park, J. H. Han, Y. Matsui, N. Nagaosa & Y. Tokura
Crystal order is not restricted to the periodic atomic array, but can also be found in electronic systems such as the Wigner crystal1 or in the form of orbital order2, stripe order3 and magnetic order. In the case of magnetic order, spins align parallel to each other in ferromagnets and antiparallel in antiferromagnets. In other, less conventional, cases, spins can sometimes form highly nontrivial structures called spin textures4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23. Among them is the unusual, topologically stable skyrmion spin texture, in which the spins point in all the directions wrapping a sphere4, 5, 6, 7. The skyrmion configuration in a magnetic solid is anticipated to produce unconventional spin–electronic phenomena such as the topological Hall effect24, 25, 26. The crystallization of skyrmions as driven by thermal fluctuations has recently been confirmed in a narrow region of the temperature/magnetic field (T–B) phase diagram in neutron scattering studies of the three-dimensional helical magnets MnSi (ref. 17) and Fe1?xCoxSi (ref. 22). Here we report real-space imaging of a two-dimensional skyrmion lattice in a thin film of Fe0.5Co0.5Si using Lorentz transmission electron microscopy. With a magnetic field of 50–70?mT applied normal to the film, we observe skyrmions in the form of a hexagonal arrangement of swirling spin textures, with a lattice spacing of 90?nm. The related T–B phase diagram is found to be in good agreement with Monte Carlo simulations. In this two-dimensional case, the skyrmion crystal seems very stable and appears over a wide range of the phase diagram, including near zero temperature. Such a controlled nanometre-scale spin topology in a thin film may be useful in observing unconventional magneto-transport effects.
