Bimerons create bimerons: proliferation and aggregation induced by currents and magnetic fields

The aggregation of topological spin textures at nano and micro scales has practical applications in spintronic technologies. Here, the authors report the in-plane current-induced proliferation and aggregation of bimerons in a bulk chiral magnet. It is found that the spin-transfer torques can induce the proliferation and aggregation of bimerons only in the presence of an appropriate out-of-plane magnetic field. It is also found that a relatively small damping and a relatively large non-adiabatic spin-transfer torque could lead to more pronounced bimeron proliferation and aggregation. Particularly, the current density should be larger than a certain threshold in order to trigger the proliferation; namely, the bimerons may only be driven into translational motion under weak current injection. Besides, the authors find that the aggregate bimerons could relax into a deformed honeycomb bimeron lattice with a few lattice structure defects after the current injection. The results are promising for the development of bio-inspired spintronic devices that use a large number of aggregate bimerons. The findings also provide a platform for studying aggregation-induced effects in spintronic systems, such as the aggregation-induced lattice phase transitions.