Observation of ν = 5/2 Fractional Quantum Hall Effect in Trilayer Graphene Proximitized by V-Doped WSe₂

Graphene has long been a test bed for observing strongly correlated phenomena owing to its 2D nature and ability to host high carrier mobility. However, the lack of intrinsic magnetism and weak spin-orbit coupling limits its ability to host strong electronic correlations. Here, observation of strongly correlated phenomena in trilayer graphene (TLG) proximitized by a ferromagnetic V-doped WSe₂ (V-WSe₂) overlayer is reported. These include the emergence of an odd- and even-denominator fractional quantum Hall state at ν  = 5/2 and reentrant integer quantum Hall effect in the hole regime of the TLG, driven by proximate magnetism from the V-WSe₂. A remarkably large activation energy gap (Δ_5/2 = 48 ± 5 K) for the 5/2 fractional state is observed, which is essential for probing its non-Abelian nature. Furthermore, the large Δ_5/2 significantly enhances its feasibility for topological quantum computation by exponentially suppressing the error rates. Additionally, the formation of three additional Dirac cones, termed Dirac "gullies," is observed, which manifest as threefold-degenerate Landau levels in magnetotransport measurements. These findings not only advance the role of magnetism in graphene-based heterostructures but also open pathways toward studying non-Abelian quasiparticles for their exotic fundamental and technological implications.