ABSTRACT
Various transitions that a magnetic Skyrmion can undergo are found in calculations using a method for climbing up the energy surface and converging onto first order saddle points. In addition to collapse and escape through a boundary, the method identifies a transition where the Skyrmion divides and forms two Skyrmions. The activation energy for this duplication process can be similar to that of collapse and escape. A tilting of the external magnetic field for a certain time interval is found to induce the duplication process in a dynamical simulation. Such a process could turn out to be an important avenue for the creation of Skyrmions in future magnetic devices.
ABSTRACT
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.