Topological superconductivity with mixed singlet-triplet pairing in moiré transition-metal-dichalcogenide bilayers

Abstract

We investigate strong coupling topological superconductivity in twisted moiré bilayer WSe${}_2$. Our approach is based on an effective $t$-$J$ model with displacement-field-dependent complex hoppings, which is treated with the variational Gutzwiller projection method. The calculated phase diagram contains domes of topologically nontrivial superconducting phases, with Chern numbers $C=\pm 2,\pm 4$. The order parameter is characterized by a mixed $d$+$id$-wave (singlet) and $p$-$ip$-wave (triplet) gap symmetry. We also report on the appearance of an additional topologically trivial extended $s$-wave and $f$-wave paired phase. As we show, by changing the electron density and displacement field, one can tune the singlet and triplet contributions to the pairing, as well as induce topological phase transitions between superconducting states characterized by different values of the Chern number. We analyze the physical origin of the reported effects and discuss it briefly in the view of new possibilities for designing unconventional superconductivity in moiré systems.

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Cited by in corpus (9)

• Theory of Correlated Insulators and Superconductor at $\nu =1$ in Twisted WSe${}_2$
• Theory of Topological Superconductivity and Antiferromagnetic Correlated Insulators in Twisted Bilayer WSe${}_2$
• Topological Chiral Superconductivity Mediated by Intervalley Antiferromagnetic Fluctuations in Twisted Bilayer WSe${}_2$
• Approximate symmetries, insulators, and superconductivity in continuum-model description of twisted WSe${}_2$
• Twistronics and moiré superlattice physics in 2D transition metal dichalcogenides
• Angular momentum of vortex-core Majorana zero modes
• Signatures of superconducting pairing driven by electron-electron interactions in moiré WSe${}_2$/WSe${}_2$ homobilayer modelled by Hubbard Hamiltonian
• Mixed-symmetry superconductivity and the energy gap
• Onset of spin-valley order and Stoner boundaries in twisted WSe${}_2$