期刊
SCIENCE ADVANCES
卷 7, 期 19, 页码 -出版社
AMER ASSOC ADVANCEMENT SCIENCE
DOI: 10.1126/sciadv.abf5299
关键词
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资金
- Simons Investigator award
- Simons Collaboration on Ultra-Quantum Matter from the Simons Foundation [651440]
- Simons Investigator Fellowship, by NSF-DMR [1411343]
- German National Academy of Sciences Leopoldina [LPDS 2018-02]
- ERC synergy grant
- Director, Office of Science, Office of Basic Energy Sciences, Materials Sciences, and Engineering Division of the U.S. Department of Energy [DE-AC02-05-CH11231, KCWF16]
- Direct For Mathematical & Physical Scien
- Division Of Materials Research [1411343] Funding Source: National Science Foundation
Topological solitons play a crucial role in insulating and superconducting behavior in stacked and twisted graphene sheets. Symmetry breaking leads to an ordered insulator, while topological solitons result in a superconductor.
Topological solitons, a class of stable nonlinear excitations, appear in diverse domains as in the Skyrme model of nuclear forces. Here, we argue that similar excitations play an important role in a remarkable material obtained on stacking and twisting two sheets of graphene. Close to a magic twist angle, insulating behavior is observed, which gives way to superconductivity on doping. Here, we propose a unifying description of both observations. A symmetry breaking condensate leads to the ordered insulator, while topological solitons in the condensate-skyrmions-are shown to be charge 2e bosons. Condensation of skyrmions leads to a superconductor, whose physical properties we calculate. More generally, we show how topological textures can mitigate Coulomb repulsion and provide a previously unexplored route to superconductivity. Our mechanism not only clarifies why several other moire materials do not show superconductivity but also points to unexplored platforms where robust superconductivity is anticipated.
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