<p>The relative twist angle between layers of near-lattice-matched van der Waals materials is critical for the emergent phenomena associated with moiré flat bands<sup><CitationRef AdditionalCitationIDS="CR2" CitationID="CR1">1</CitationRef>–<CitationRef CitationID="CR3">3</CitationRef></sup>. However, the concept of angle rotation control is not exclusive to moiré superlattices in which electrons directly experience a twist-angle-dependent periodic potential. Instead, it can also be used to induce programmable symmetry-breaking perturbations with the goal of stabilizing desired correlated states. Here we experimentally demonstrate ‘moiréless’ twist-tuning of superconductivity together with other correlated orders in Bernal bilayer graphene proximitized by tungsten diselenide. The precise alignment between the two materials systematically controls the strength of induced Ising spin–orbit coupling (SOC), profoundly altering the phase diagram. As Ising SOC is increased, superconductivity onsets at a higher displacement field and features a higher critical temperature, reaching up to 0.5 K. Within the main superconducting dome and in the strong Ising SOC limit, we find an unusual phase transition characterized by a nematic redistribution of holes among trigonally warped Fermi pockets and enhanced resilience to in-plane magnetic fields. The superconducting behaviour is theoretically compatible with the prominent role of interband interactions between symmetry-breaking Fermi pockets. Moreover, we identify two additional superconducting regions, one of which descends from an inter-valley coherent normal state and shows a Pauli-limit violation ratio exceeding 40, among the highest for all known superconductors<sup><CitationRef AdditionalCitationIDS="CR5 CR6" CitationID="CR4">4</CitationRef>–<CitationRef CitationID="CR7">7</CitationRef></sup>. Our results provide insights into ultraclean graphene superconductors and underscore the potential of utilizing moiréless-twist engineering across a wide range of van der Waals heterostructures.</p>

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Twist-programmable superconductivity in spin–orbit-coupled bilayer graphene

  • Yiran Zhang,
  • Gal Shavit,
  • Huiyang Ma,
  • Youngjoon Han,
  • Chi Wang Siu,
  • Ankan Mukherjee,
  • Kenji Watanabe,
  • Takashi Taniguchi,
  • David Hsieh,
  • Cyprian Lewandowski,
  • Felix von Oppen,
  • Yuval Oreg,
  • Stevan Nadj-Perge

摘要

The relative twist angle between layers of near-lattice-matched van der Waals materials is critical for the emergent phenomena associated with moiré flat bands13. However, the concept of angle rotation control is not exclusive to moiré superlattices in which electrons directly experience a twist-angle-dependent periodic potential. Instead, it can also be used to induce programmable symmetry-breaking perturbations with the goal of stabilizing desired correlated states. Here we experimentally demonstrate ‘moiréless’ twist-tuning of superconductivity together with other correlated orders in Bernal bilayer graphene proximitized by tungsten diselenide. The precise alignment between the two materials systematically controls the strength of induced Ising spin–orbit coupling (SOC), profoundly altering the phase diagram. As Ising SOC is increased, superconductivity onsets at a higher displacement field and features a higher critical temperature, reaching up to 0.5 K. Within the main superconducting dome and in the strong Ising SOC limit, we find an unusual phase transition characterized by a nematic redistribution of holes among trigonally warped Fermi pockets and enhanced resilience to in-plane magnetic fields. The superconducting behaviour is theoretically compatible with the prominent role of interband interactions between symmetry-breaking Fermi pockets. Moreover, we identify two additional superconducting regions, one of which descends from an inter-valley coherent normal state and shows a Pauli-limit violation ratio exceeding 40, among the highest for all known superconductors47. Our results provide insights into ultraclean graphene superconductors and underscore the potential of utilizing moiréless-twist engineering across a wide range of van der Waals heterostructures.