Phonon or electronic pairing in rhombohedral trilayer and Bernal bilayer graphene · revision history

Revision 2

Accepted · core change · record

Changes against revision 1:

Title
Phonon or electronic pairing in rhombohedral trilayer and Bernal bilayer graphene
Plain
Graphene with three layers in staircase stacking, and ordinary two-layer graphene, superconduct at very low electron densities without any moire pattern, and it is disputed whether lattice vibrations or electron interactions cause the pairing.
Precise · changed · core
Revision 1: Rhombohedral trilayer graphene superconducts with $T_{c}$ up to about 100 mK next to isospin-symmetry-breaking transitions (Zhou et al., Nature, 2021, doi:10.1038/s41586-021-03926-0), and Bernal bilayer graphene superconducts under in-plane magnetic field or with spin-orbit coupling induced by an adjacent WSe2 layer. Determine whether pairing is mediated by acoustic phonons (Chou et al., PRL 127, 187001, 2021) or by isospin fluctuations or Kohn-Luttinger repulsion (e.g., Chatterjee et al., Nature Communications, 2022, doi:10.1038/s41467-022-33561-w). An answer reproduces $T_{c}(n,D)$ in both systems and predicts the response to gate screening.
Revision 2: Rhombohedral trilayer graphene superconducts with $T_{c}$ up to about 100 mK next to isospin-symmetry-breaking transitions (Zhou et al., Nature, 2021, doi:10.1038/s41586-021-03926-0), and Bernal bilayer graphene superconducts under in-plane magnetic field or with spin-orbit coupling induced by an adjacent $\mathrm{WSe_2}$ layer. Determine whether pairing is mediated by acoustic phonons (Chou et al., PRL 127, 187001, 2021) or by isospin fluctuations or Kohn-Luttinger repulsion (e.g., Chatterjee et al., Nature Communications, 2022, doi:10.1038/s41467-022-33561-w). An answer reproduces $T_{c}(n,D)$ in both systems and predicts the response to gate screening.
Settled by
$T_{c}$ measured in devices with different gate-to-sample distances (screening suppresses electronic but not phonon pairing), compared with parameter-free calculations of both mechanisms.
Kind
phenomenon
Answer type
mechanism
References
(empty)
Literature status
contested
Status note
Phonon and electronic theories both remain in use as of 2026.
Posed since
2021

Decisions