Higher-Winding Fractionalization

Abstract

Higher-winding skyrmion textures can generate emergent magnetic fields with multiple flux quanta per unit cell. This opens an intriguing route toward fractionalization, allowing fractionalized quantum anomalous Hall states to arise even at integer filling of the microscopic unit cell. We show that, in this setting, increasing lattice-scale inhomogeneity of the emergent magnetic field drives a Berezinskii--Kosterlitz--Thouless (BKT) transition between a fractionalized liquid and a crystalline dielectric state. This transition carries a topological signature: under flux insertion, the many-body polarization defines a quantized winding number that is nonzero in the fractionalized phase and vanishes in the dielectric crystal.