Isospin magnetism and spin-polarized superconductivity in Bernal bilayer graphene
- University of California, Santa Barbara, CA (United States); OSTI
- University of California, Santa Barbara, CA (United States)
- National Institute for Materials Science, Tsukuba (Japan)
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. Superconductivity occurs near a symmetry-breaking transition and exists exclusively above the B∥ limit expected of a paramagnetic superconductor with the observed transition critical temperature TC ≈ 30 millikelvins, consistent with a spin-triplet order parameter.
- Research Organization:
- University of California, Santa Barbara, CA (United States)
- Sponsoring Organization:
- Army Research Office (ARO); Gordon and Betty Moore Foundation; Japan Society for the Promotion of Science (JSPS); Ministry of Education, Culture, Sports, Science and Technology (MEXT); Packard Foundation; USDOE Office of Science (SC)
- Grant/Contract Number:
- SC0020043
- OSTI ID:
- 1980741
- Journal Information:
- Science, Journal Name: Science Journal Issue: 6582 Vol. 375; ISSN 0036-8075
- Publisher:
- AAASCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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