Device geometry dependent deterministic skyrmion generation from a skyrmionium.

A magnetic skyrmionium can be perceived as an association of two magnetic skyrmions with opposite topological charges. In this work, we have investigated the transformation of skyrmionium into multi-skyrmionic states via domain wall pairs in three different devices with variable geometric configurations. The same device geometries are considered for single ferromagnetic layer and synthetic antiferromagnetic system. It is observed that by tuning the current density, deterministic generation of skyrmions is possible via the spin transfer torque. The proposed device is efficiently adjustable to change the number of skyrmions also at room temperature. The results may lead to development of skyrmion-based devices for neuromorphic and unconventional computing.