Topological Hall Effect — Skyrmion

Real-space Berry phase from magnetic skyrmion spin texture

Topological charge Q = —
A magnetic skyrmion is a topologically protected spin texture with winding number Q = ±1. Conduction electrons adiabatically following the skyrmion spin accumulate a real-space Berry phase Φ_B = 4πQ per skyrmion. This acts as an emergent magnetic flux B_eff = Φ₀·Q/A, deflecting electrons and producing a topological Hall resistivity ρ_THE ∝ Q — measurable even without spin-orbit coupling.