3D skyrmion strings and their melting dynamics revealed via scalar-field electron tomography

Abstract

Two-dimensional skyrmion, a topological spin texture, has been extensively investigated in non-centrosymmetric magnets. It is thermodynamically stable in bulk materials and can extend perpendicularly to the spin-rotating plane, forming the three-dimensional (3D) skyrmion string that occasionally terminates inside the bulk or at its surfaces, thereby producing spin (anti)hedgehogs. While magnetically manipulated skyrmion strings have been demonstrated thus far, an understanding of metastable skyrmion strings and their melting dynamics remain elusive. The challenge arises from the absence of a suitable 3D magnetic imaging technique that is capable of tracking their dynamics while varying the temperature. Here, we show a high-resolution 3D phase imaging to show the metastable skyrmions and their melting dynamics accompanied by the emergence of (anti)hedgehogs over a temperature range from 95 K to room temperature in helimagnets.