Vlasov Sergei M, Uzdin Valery M, Leonov Andrey O
St. Petersburg State University, St. Petersburg, 198504, Russia. ITMO University, St. Petersburg, 197101, Russia.
J Phys Condens Matter. 2020 May 1;32(18):185801. doi: 10.1088/1361-648X/ab6e40.
Magnetic chiral skyrmions are particle-like excitations with a topological charge, which are currently considered as promising objects for the next generation of magnetic memory, logic, and neuromorphic devices. In three-dimensional systems, they can form rather complex topological structures. In bulk helimagnets, elongated skyrmion tubes can be ordered either perpendicularly or parallel to an external magnetic field and such configurations coexist in a specific range of fields. We have shown that with an increase in the magnetic field, the transition from perpendicular to parallel ordering in a 3D skyrmion dimer occurs through an intermediate state with mutually orthogonal skyrmion tubes. In the system with three and more skyrmion tubes, we uncovered a surprisingly large diversity of superstructures and systemized the principles of their formation. The nascent conical state is shown to induce the field-dependent switch between favored skyrmion clusters and underlies attracting inter-skyrmion potential. We argue that our numerical simulations on skyrmion clusters are valid in a parameter range corresponding to the A-phase region of cubic helimagnets. Moreover, skyrmionic superstructures constitute a novel concept of spintronic devices based on gapless skyrmion motion along with each other.
磁性手性斯格明子是具有拓扑电荷的类粒子激发，目前被认为是下一代磁存储器、逻辑器件和神经形态器件的有前途的研究对象。在三维系统中，它们可以形成相当复杂的拓扑结构。在体螺旋磁体中，细长的斯格明子管可以垂直或平行于外部磁场排列，并且这种构型在特定的磁场范围内共存。我们已经表明，随着磁场的增加，三维斯格明子二聚体中从垂直排列到平行排列的转变是通过具有相互正交斯格明子管的中间状态发生的。在具有三个及更多斯格明子管的系统中，我们发现了令人惊讶的大量超结构，并将它们的形成原理系统化。新出现的锥形状态被证明会诱导受青睐的斯格明子簇之间的场依赖开关，并构成吸引斯格明子间势的基础。我们认为，我们对斯格明子簇的数值模拟在对应于立方螺旋磁体A相区域的参数范围内是有效的。此外，斯格明子超结构构成了基于无隙斯格明子相互运动的自旋电子器件的新概念。
