Excitonic and magnetic phases in doped WTe${}_2$ monolayers: a Hartree-Fock approach

Abstract

Transport and local spectroscopy measurements have revealed that monolayers of tungsten ditelluride ($1T^{\prime }$-WTe${}_2$) display a quantum spin Hall effect and an excitonic gap at neutrality, besides becoming superconducting at low electron concentrations. With the aim of studying the competition among different broken-symmetry phases upon electron doping, we have performed extensive Hartree-Fock calculations as a function of electron density and Coulomb interaction strength. At charge neutrality, we reproduce the emergence of a spin density wave and a spin spiral state surrounding a quantum spin Hall insulator at intermediate interaction strengths. For stronger interactions, the spin spiral is disrupted by a state breaking both inversion and time-reversal symmetries (but not their product) before the system becomes a trivial band insulator. With electron doping the quantum spin Hall insulator evolves into an easy-plane ferromagnet due to a Stoner-like instability of the conduction band. This phase competes energetically with the spin spiral state. We discuss how our results may help to interpret past and future measurements.

arXiv comment11 pages, 8 figures

References in corpus (27)

• Quantum Spin Hall Effect and Topological Field Effect Transistor in Two-Dimensional Transition Metal Dichalcogenides
• Realization of Quantum Spin Hall State in Monolayer 1T'-WTe2
• Observation of the Quantum Spin Hall Effect up to 100 Kelvin in a Monolayer Crystal
• Edge conduction in monolayer WTe2
• Electrically Tunable Low Density Superconductivity in a Monolayer Topological Insulator
• Gate-induced superconductivity in a monolayer topological insulator
• Electronic properties of single-layer and multilayer transition metal dichalcogenides $M{X}_2$ ($M=$ Mo, W and $X=$ S, Se)
• Superfluid Spin Transport through Easy-Plane Ferromagnetic Insulators
• On the quantum spin Hall gap of monolayer 1T'-WTe2
• Theory of 2D crystals: graphene and beyond
• Evidence for equilibrium excitons and exciton condensation in monolayer WTe2
• First order character and observable signatures of topological quantum phase transitions
• Dissipationless Spin Transport in Thin Film Ferromagnets
• Interplay of exciton condensation and quantum spin Hall effect in InAs/GaSb bilayers
• Observation of Coulomb gap in the quantum spin Hall candidate single-layer 1T'-WTe${}_2$
• Continuous and discontinuous topological quantum phase transitions
• Time Reversal Symmetric Topological Exciton Condensate in Bilayer HgTe Quantum Wells
• Spin Superfluidity in the $\nu =0$ Quantum Hall State of Graphene
• Strong Correlation Effects on Topological Quantum Phase Transitions in Three Dimensions
• Custodial glide symmetry of quantum spin Hall edge modes in WTe${}_2$ monolayer
• Time-Reversal Symmetry-Breaking Nematic Insulators near Quantum Spin Hall Phase Transitions
• Unconventional Superconducting Quantum Criticality in Monolayer WTe2
• Theory of competing excitonic orders in insulating WTe${}_2$ monolayers
• Exciton topology and condensation in a model quantum spin Hall insulator
• Exciton condensation in strongly correlated quantum spin Hall insulators
• A gate-tunable quantum phase transition in a topological excitonic insulator
• Breakdown of helical edge state topologically protected conductance in time-reversal-breaking excitonic insulators