Observation of two independent skyrmion phases in a chiral magnetic material
Observation of two independent skyrmion phases in a chiral magnetic material
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DOI：
10.1038/s41567-018-0184-y
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发表时间：
2018-09-01
期刊：
影响因子：
19.6
通讯作者：
Pfleiderer, C.
中科院分区：
文献类型：
--
作者：
Chacon, A.;Heinen, L.;Pfleiderer, C.
磁性材料可以容纳Skyrmions，这在拓扑上是不平凡的自旋织构。在具有立方晶格对称性的手性磁体中，以前观察到的所有Skyrmion相都需要热涨落才能在块体材料中变得热力学稳定，因此只在相对较高的温度下存在，接近日磁转变温度。其他稳定机制需要降低立方晶体的对称性。在这里，我们报告了在低温和外加磁场存在的情况下，在Cu2OSeO3中发现了第二个Skyrmion相。新的Skyrmion相在热力学上与众所周知的近乎各向同性的高温相分离，相反，当外部磁场仅沿<；100>；晶轴取向时，新的Skyrmion相存在。理论模型提供的证据表明，稳定机制是由众所周知的立方各向异性项给出的，并解释了亚稳螺旋线偏离外加磁场的额外观测。同一材料中两个不同的Skyrmion相的识别和潜在机制的类属特征为发现、设计和操纵拓扑自旋织构提供了一条新的途径。
Magnetic materials can host skyrmions, which are topologically non-trivial spin textures. In chiral magnets with cubic lattice symmetry, all previously observed skyrmion phases require thermal fluctuations to become thermodynamically stable in bulk materials, and therefore exist only at relatively high temperature, close to the helimagnetic transition temperature. Other stabilization mechanisms require a lowering of the cubic crystal symmetry. Here, we report the identification of a second skyrmion phase in Cu2OSeO3 at low temperature and in the presence of an applied magnetic field. The new skyrmion phase is thermodynamically disconnected from the well-known, nearly isotropic, high-temperature phase, and exists, in contrast, when the external magnetic field is oriented along the < 100 > crystal axis only. Theoretical modelling provides evidence that the stabilization mechanism is given by well-known cubic anisotropy terms, and accounts for an additional observation of metastable helices tilted away from the applied field. The identification of two distinct skyrmion phases in the same material and the generic character of the underlying mechanism suggest a new avenue for the discovery, design and manipulation of topological spin textures.