Chiral and nodal superconductors in t-J model with valley contrasting flux on triangular moiré lattice

Abstract

Recent experimental progresses have made it possible to simulate spin 1/2 Hubbard model on triangular lattice in moiré materials formed by transition metal dichalcogenide (TMD) heterobilayer or homobilayer. In twisted TMD homobilayer, a vertical electric field can induce a valley contrasting flux in the hopping term. In this paper we study possible superconductors from a t-J model with valley contrasting flux $\Phi$ using the slave boson mean field theory. We obtain a phase diagram with doping $x$ and $\Phi$. A finite $\Phi$ breaks spin rotation symmetry and the pairing symmetry is a superposition of spin singlet $d-id$ and spin triplet $p+ip$. There are two topological phase transitions when tuning $\Phi$ from $0$ to $\pi$, with three Dirac nodes at one transition and one single Dirac node at the other transition. We also discuss the effects of van Hove singularity and a three-site correlated hopping term on the pairing strength. Lastly, we demonstrate that a small anisotropy term breaking the $C_3$ rotation can lead to a time reversal invariant nodal superconductor connected to the $d_{x^2-y^2}$ superconductor on square lattice.

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Cited by in corpus (10)

• Superconductivity in twisted bilayer WSe${}_2$
• Superconductivity in twisted transition metal dichalcogenide homobilayers
• Theory of Correlated Insulators and Superconductor at $\nu =1$ in Twisted WSe${}_2$
• Singlet, Triplet and Pair Density Wave Superconductivity in the Doped Triangular-Lattice Moiré System
• Superconductivity in twisted WSe${}_2$ from topology-induced quantum fluctuations
• Theory of Topological Superconductivity and Antiferromagnetic Correlated Insulators in Twisted Bilayer WSe${}_2$
• Approximate symmetries, insulators, and superconductivity in continuum-model description of twisted WSe${}_2$
• Moiré Band Engineering in Twisted Trilayer WSe2
• Twistronics and moiré superlattice physics in 2D transition metal dichalcogenides
• Onset of spin-valley order and Stoner boundaries in twisted WSe${}_2$