Isospin magnetism and spin-polarized superconductivity in Bernal bilayer graphene

In conventional superconductors, Cooper pairing occurs between electrons of opposite spin. We observe spin-polarized superconductivity in Bernal bilayer graphene when doped to a saddle-point van Hove singularity generated by a large applied perpendicular electric field. We observe a cascade of electrostatic gate-tuned transitions between electronic phases distinguished by their polarization within the isospin space defined by the combination of the spin and momentum-space valley degrees of freedom. Although all of these phases are metallic at zero magnetic field, we observe a transition to a superconducting state at finite magnetic field B ‖ ≈ 150 milliteslas applied parallel to the two-dimensional sheet.…

• UD
  U.S. Department of Energy

  Award: DE-SC0020043
• GA
  Gordon and Betty Moore Foundation

  Award: GBMF9471
• MO
  Ministry of Education, Culture, Sports, Science and Technology

  Awards: 19H05790, 21H05233, JPMXP0112101001
• JS
  Japan Society for the Promotion of Science

  Awards: JPMXP0112101001, 19H05790, 20H00354, 21H05233
• AR
  Army Research Office

  Awards: W911NF-17-1-0323, W911NF