A liquid-crystal analogue of the skyrmion Hall effect

Topology provides a unifying framework across disciplines, ranging from particle physics and cosmology to condensed-matter systems. In condensed matter, one of its most striking manifestations is the skyrmion Hall effect, where skyrmions—emergent spin configurations characterized by a conserved topological charge—acquire a transverse velocity under driving. Recent advances have revealed that chiral liquid crystals host a wide variety of topological solitons, including torons and skyrmion tubes. Here we show that such solitons exhibit a Hall-like response under shear flow, undergoing a transverse drift away from the shear direction. Our theoretical analysis predicts a weak net transverse mass flow whose magnitude scales as the cube of the shear rate. However, tracer-particle experiments and numerical simulations show that the solitons do not behave as passive tracers of this flow: their transverse motion is much stronger, and in simulations, it occurs opposite to the net transverse mass current. A liquid-crystal analogue of the Thiele equation provides a simple physical framework that highlights the central role of flow vorticity in the effect. These results establish a liquid-crystal analogue of the skyrmion Hall effect and open pathways for microfluidic technologies that exploit soft topological solitons as functional building blocks.