Creation and observation of Hopfions in magnetic multilayer systems

Topological solitons have been studied for decades in classical field theories, and started recently to impact condensed matter physics. Among those solitons, magnetic skyrmions are two-dimensional particle-like objects with a continuous winding of the magnetization, Hopfions three-dimensional topological that can be formed from closed loop twisted skyrmion string. Whereas intense research is underway towards fundamental understanding potential applications advanced storage logic devices, experimental creation confirmation has elusive so far. Theoretical models suggest stabilized frustrated or chiral systems, target skymions transformed into by adapting their perpendicular anisotropy. Here, we present evidence were created Ir/Co/Pt multilayers shaped nanoscale disks, which known host skyrmions. The spin texture, distinguishes was confirmed combining two element-specific X-ray microscopy techniques about 20-30nm lateral resolution, using circular dichroism effect as contrast mechanism surface-sensitive photoemission electron bulk-sensitive soft x-ray transmission microscopy. We anticipate these results will stimulate further investigations different topologies application spintronics devices.