Press Releases

2018.05.29

Aggregation and collapse dynamics of skyrmions in a non-equilibrium state:Tomoyuki Yokouchi(D3, at the time), Assistant Professor Naoya Kanazawa, Associate Professor Fumitaka Kagawa, Professor Yoshinori Tokura, Department of Applied Physics, and other researchers.

Magnetic skyrmions have attracted attention because of their emergent electromagnetic properties. In particular, non-equilibrium-state skyrmions, which are protected by topology and hence can exist over a wider temperature–magnetic-field region, show promise for possible practical applications, but their dynamics remain elusive. Here, we report the observation of a magnetic-field-induced dynamical transition from the metastable hexagonal-lattice skyrmion crystal (SkX) at a zero bias-field to an amorphous state via the densely vacancy-populated SkX. With decreasing field, on the other hand, the aggregate transforms from ‘random particles’ to ‘microcrystals’ of skyrmions in a non-equilibrium state, in analogy to colloidal crystallization, and subsequently undergoes a topologically distinct phase separation between the SkX and helical/conical domains accompanied by topological defects. These observations directly demonstrate the aggregation and collapse dynamics of metastable skyrmions and may provide a route to other nontrivial topological phenomena such as the zero-magnetic-field topological Hall effect.

 

Nature Physics:https://www.nature.com/articles/s41567-018-0155-3