Charge Excitations at Landau Level Crossings in WSe 2 -Encapsulated Bilayer Graphene

Abstract Skyrmions—topological spin/pseudospin textures—are natural charge excitations of quantum Hall (QH) ferromagnets. In a WSe 2 -encapsulated bilayer graphene (BLG) heterostructure, we tune the valley-only Landau level (LL) crossings at ν = ±3 with an out-of-plane displacement field ( D field) and use them as a platform to probe valley excitations. Activation gap measurements reveal a finite gap at degeneracy that rises sharply with D field near the crossing and exceeds the single-particle valley susceptibility, suggesting valley-skyrmion charge excitations. We quantify the skyrmion size and elucidate the mechanism governing its magnetic-field dependence. Similar behavior appears at valley-orbital and valley-spin entangled crossings ( ν = ±2 and ν = ±1, respectively). These results suggest controlled valley-skyrmion formation in BLG and open a route to engineering interacting multicomponent QH ferromagnets with tunable spin/pseudospin textures.