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Correlation-Induced Triplet Pairing Superconductivity in Graphene-Based Moiré Systems
Yang-Zhi Chou1, Fengcheng Wu2, Jay D Sau1
1Condensed Matter Theory Center and Joint Quantum Institute, Department of Physics, University of Maryland, College Park, Maryland 20742, USA.
Physical Review Letters
|December 3, 2021
Summary
Researchers explored triplet-pairing superconductivity in twisted trilayer graphene, finding f-wave pairing favored by its unique structure. This superconducting state is robust, time-reversal symmetric, and distinct from other known triplet superconductors.
Area of Science:
- Condensed Matter Physics
- Materials Science
Background:
- Magic-angle twisted trilayer graphene exhibits complex electronic properties, including potential non-spin-singlet superconductivity.
- Understanding the pairing mechanism in such systems is crucial for novel quantum phenomena.
Purpose of the Study:
- Investigate triplet-pairing superconductivity in a correlation-induced spin-fermion model of Dirac fermions.
- Explore the role of spin, valley, and sublattice degrees of freedom in superconductivity.
- Analyze the impact of in-plane magnetic fields on the superconducting state.
Main Methods:
- Utilized a spin-fermion model for Dirac fermions.
- Incorporated spin, valley, and sublattice degrees of freedom.
- Analyzed the effects of a small in-plane magnetic field.
Main Results:
- Identified f-wave pairing as the favored superconducting state due to the valley-sublattice structure.
- Characterized the superconducting state as time-reversal symmetric, fully gapped, and nontopological.
- Observed partial polarization and slight enhancement of transition temperature under an in-plane magnetic field.
Conclusions:
- The findings provide a theoretical framework for triplet-pairing superconductivity in graphene-based moiré systems.
- The discovered f-wave superconductivity is fundamentally distinct from that in Helium-3 or ferromagnetic superconductors.
- Results offer insights into exotic superconductivity driven by electronic correlations.
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