Twisted Nodal Superconductors

Phys. Rev. Lett. 130, 186001 (2023); Phys. Rev. B 107, 174506 (2023);
arXiv:2108.13455; arXiv:2108.13456

Momentum space schematic of a twisted nodal superconductor appropriate for high-Tc cuprate bilayer. Inset shows the current-induced opening of a topological gap.

Motivated by the recent achievements in the realization of strongly correlated and topological phases in twisted van der Waals heterostructures, we have studied the low-energy properties of a twisted bilayer of nodal superconductors. The highlight of the work is that the application of an interlayer current transforms the system into a topological superconductor, opening a topological gap and resulting in a quantized thermal Hall effect with gapless, neutral edge modes. Additionally, close to the “magic angle,” where the Dirac velocity of the quasiparticles is found to vanish, a correlated superconducting state breaking time-reversal symmetry is shown to emerge. Estimates for a number of superconducting materials, such as cuprate, heavy fermion, and organic nodal superconductors, show that twisted bilayers of nodal superconductors can be readily realized with current experimental techniques.

Phys. Rev. Lett. 130, 186001 (2023); Phys. Rev. B 107, 174506 (2023);
arXiv:2108.13455; arXiv:2108.13456

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