ArXiv · 2026
Scanning-tunnelling spectroscopy at the AB and BA stacking points of magic-angle twisted bilayer graphene should reveal two asymmetric Van Hove peaks separated by Δₛₚₗᵢₜ≈ 171~meV – a splitting absent from the standard Bistritzer–MacDonald spectrum. We show this signature arises naturally from the Hermitian ordering correction of the Dirac Hamiltonian with spatially varying mass, which generates an emergent Aharonov–Bohm flux of h/(2e) at each zero of the effective mass m_eff(r)=w|f(r)|. In the chiral limit, the interlayer coupling is locally diagonalised by a spatially dependent unitary transformation; the ordering term H_ord=-i/2σ· ∇ln m_eff then develops a 1/r singularity at the AB/BA stacking points, where m_eff vanishes. The splitting scales as √θ – distinguishing it from correlation-driven gaps (∝θ or ∝ 1/θ) – is gate-voltage independent, and is spatially localised within r_c≈ 2.1~nm of each AB/BA point. Within the local asymptotic theory near the zeros of eff, the ordering-corrected zero mode acquires parabolic-cylinder character D_(-1/2). The spatially resolved AB/BA spectrum reported in recent STM studies of magic-angle TBG has not been analysed for two-peak structure and constitutes an immediate experimental test; the predicted cell-averaged broadening of ≈ 14~meV is consistent with the 16~meV discrepancy between existing STM data and the BM tight-binding prediction.
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