Orbital Limit and Gaussian Fluctuation Effects in Flat Band Superconductors with PseudoMagnetic Fields

Abstract

In this work, we study a molecular graphene model on the top of a superconductor in the presence of pseudomagnetic fields induced by coplanar strain fields. With the pseudomagnetic fields and the attractive interaction induced from the substrate, a flat band superconductor can be achieved according to mean field analysis on the effective Hamiltonian. Based on a semiclassical approximation, we first show that the orbital limit is hugely enhanced by the pseudomagnetic fields. The physical reason is that the orbital angular momenta locking at $K$ and $K^{\prime }$ valleys due to the pseudomagnetic fields suppress the orbital magnetization from external magnetic fields. Considering the vanishing band width in this system, we then study the effects of Gaussian fluctuations in both Hartree and pairing channels. We show that in the dilute limit, the phase transition is dominated by collective modes with critical temperatures much lower than the mean field results. At half filling, our method gives no corrections to the mean field critical temperatures.

References in corpus (31)

• Magic-angle graphene superlattices: a new platform for unconventional superconductivity
• Correlated Insulator Behaviour at Half-Filling in Magic Angle Graphene Superlattices
• Energy gaps, topological insulator state and zero-field quantum Hall effect in graphene by strain engineering
• Evidence of Ising pairing in superconducting NbSe${}_2$ atomic layers
• Two Dimensional Ising Superconductivity in Gated MoS${}_2$
• Topological nodal line semimetals with and without spin-orbital coupling
• Superfluidity in topologically nontrivial flat bands
• Superconductivity protected by spin-valley locking in ion-gated MoS2
• High-temperature surface superconductivity in topological flat-band systems
• From Nagaoka's ferromagnetism to flat-band ferromagnetism and beyond: An introduction to ferromagnetism in the Hubbard model
• Ferromagnetism in the Hubbard Model-- Examples from Models with Degenerate Single-Electron Ground States
• Geometric origin of superfluidity in the Lieb lattice flat band
• Generating quantizing pseudomagnetic fields by bending graphene ribbons
• The Insulating State of Matter: A Geometrical Theory
• Band geometry, Berry curvature and superfluid weight
• Strain-induced partially flat band, helical snake states, and interface superconductivity in topological crystalline insulators
• Quantum Fluctuations in the Superfluid State of the BCS-BEC Crossover
• Effective theory and emergent $SU(2)$ symmetry in the flat bands of attractive Hubbard models
• Superconducting Transitions in Flat Band Systems
• High-temperature surface superconductivity in rhombohedral graphite
• Pairing fluctuations and the superfluid density through the BCS-BEC crossover
• Effective action for Superconductors and BCS-Bose crossover
• Quantum fluctuations in the BCS-BEC crossover of two-dimensional Fermi gases
• Flat band superconductivity in strained Dirac materials
• Superconducting States in pseudo-Landau Levels of Strained Graphene
• From Standard Model of particle physics to room-temperature superconductivity
• Microscopic Functional Integral Theory of Quantum Fluctuations in Double-Layer Quantum Hall Ferromagnets
• Finite-temperature quantum fluctuations in two-dimensional Fermi superfluids
• Pseudogap and preformed pairs in the imbalanced Fermi gas in two dimensions
• Surface superconductivity in multilayered rhombohedral graphene: Supercurrent
• Composite bosons in the 2D BCS-BEC crossover from Gaussian fluctuations