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Geometric superfluid stiffness of Kekul\'e superconductivity in magic-angle twisted bilayer graphene

Superconductivity 2026-03-27 v1 Materials Science Strongly Correlated Electrons

Abstract

Superconductivity in twisted graphene is probed by tunneling spectroscopy and superfluid stiffness, two observables that access the same order parameter from complementary perspectives. We show that a finite-momentum pair-density-wave (PDW) state, consistent with reported Kekul\'e signatures, reconciles substantial low-energy tunneling weight with an approximately T2T^2 suppression of the low-temperature superfluid stiffness. The PDW order produces a Bogoliubov Fermi surface and finite zero-bias conductance. The same gapless quasiparticles also enter the geometric superfluid response, yielding a low-temperature stiffness suppression that persists in the flat-band limit. We further predict that, under density or displacement-field tuning, enhanced residual zero-bias conductance should accompany reduced low-temperature stiffness, providing a direct experimental link between tunneling spectroscopy and phase rigidity in twisted graphene.

Keywords

Cite

@article{arxiv.2603.24766,
  title  = {Geometric superfluid stiffness of Kekul\'e superconductivity in magic-angle twisted bilayer graphene},
  author = {Ke Wang and Qijin Chen and Rufus Boyack and K. Levin},
  journal= {arXiv preprint arXiv:2603.24766},
  year   = {2026}
}

Comments

14 pages, 4 figures