Evolution of Emergent Monopoles into Magnetic Skyrmion Strings

Topological defects are fundamental concepts in physics,but littleis known about the transition between distinct types across differentdimensionalities. In topological magnetism, as in field theory, thetransition between 1D strings and 0D monopoles is a key process whoseobservation has remained elusive. Here, we introduce a novel mechanismthat allows for the controlled stabilization of emergent monopolesand show that magnetic skyrmion strings can be folded into monopoles.Conversely, they act as seeds out of which the entire string structurecan unfold, containing its complete information. In chiral magnets,this process can be observed by resonant elastic X-ray scatteringwhen the objects are in proximity to a polarized ferromagnet, wherebya pure monopole lattice is emerging on the surface. Our experimentalproof of the reversible evolution from monopole to string sheds newlight on topological defects and establishes the emergent monopolelattice as a new 3D topological phase.