Experimental observation of chiral magnetic bobbers in B20-type FeGe
Experimental observation of chiral magnetic bobbers in B20-type FeGe
复制标题
B20型FeGe中手性磁浮子的实验观察
DOI：
10.1038/s41565-018-0093-3
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发表时间：
2018-06-01
影响因子：
38.3
通讯作者：
Dunin-Borkowski, Rafal E.
中科院分区：
文献类型：
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作者：
Zheng, Fengshan;Rybakov, Filipp N.;Dunin-Borkowski, Rafal E.
手性磁性skyrmions（1，2）是纳米级的涡旋状自旋纹理，在铁磁体中形成，由于强自旋轨道耦合和晶体的反转对称性破缺，铁磁体支持Dzyaloshinskiii-Moriya相互作用（π）。与允许形成各种二维（2D）skyrmions的其他系统（5，6）形成鲜明对比，在手性磁体中，双光子的存在通常会阻止不同类型拓扑激发的稳定性和共存性（7）。最近，一种新型的局部粒子状物体-手性bobber（ChB）-在理论上预测在这样的材料中（8）。然而，它的存在尚未得到实验验证。在这里，我们报告的直接观察ChBs的B20型FeGe薄膜的定量离轴电子全息（EH）。我们确定的温度-磁场相图中存在的ChBs的一部分，并区分两种机制，其成核。此外，我们表明，ChBs能够共存的skyrmions在很宽的参数范围内，这表明他们可能的实际应用中的新型磁性固态存储器设备，其中一个流的二进制数据位可以编码的序列的skyrmions和bobbers。
Chiral magnetic skyrmions(1,2) are nanoscale vortex-like spin textures that form in the presence of an applied magnetic field in ferromagnets that support the Dzyaloshinskii-Moriya interaction (DMI) because of strong spin-orbit coupling and broken inversion symmetry of the crystal(3,4). In sharp contrast to other systems(5,6) that allow for the formation of a variety of two-dimensional (2D) skyrmions, in chiral magnets the presence of the DMI commonly prevents the stability and coexistence of topological excitations of different types(7). Recently, a new type of localized particle-like object-the chiral bobber (ChB)-was predicted theoretically in such materials(8). However, its existence has not yet been verified experimentally. Here, we report the direct observation of ChBs in thin films of B20-type FeGe by means of quantitative off-axis electron holography (EH). We identify the part of the temperature-magnetic field phase diagram in which ChBs exist and distinguish two mechanisms for their nucleation. Furthermore, we show that ChBs are able to coexist with skyrmions over a wide range of parameters, which suggests their possible practical applications in novel magnetic solid-state memory devices, in which a stream of binary data bits can be encoded by a sequence of skyrmions and bobbers.