Two-dimensional charge density wave TaX${}_2$ (X=S, Se, Te) from first principles

Abstract

Transition metal dichalcogenides are rich in their structural phases, e.g. 1T-TaS2 and 1T-TaSe2 form charge density wave (CDW) under low temperature with interesting and exotic properties. Here, we present a systematic study of different structures in two-dimensional TaX2 (X=S, Se, Te) using density functional theory calculations with consideration of van der Waals interaction. All the normal phases present metal characteristics with various ground state and magnetic properties. The lattice reconstruction of CDW drastically affects the electronic and structural characteristics of 1T-TaS2 and 1T-TaSe2, leading to a transition from metal to insulator and an emergence of magnetic moment within periodic atomic clusters called the Star of David. The evaluated Heisenberg couplings indicate the weak ferromagnetic coupling between the clusters in monolayer. Furthermore, in bilayer commensurate CDW cases, we find intriguing phenomenon of the varying magnetic properties with different stacking orders. The magnetic moment in each layer disappears when two layers are coupled, but may sustain in certain stackings of interlayer antiferromagnetic configurations.

References in corpus (4)

• Gate-tunable Phase Transitions in 1T-TaS${}_2$
• Tuning Electronic and Magnetic Properties of Early Transition Metal Dichalcogenides via Tensile Strain
• Band insulator to Mott insulator transition in 1T-TaS${}_2$
• Identification of the Mott insulating CDW state in 1T-TaS${}_2$

Cited by in corpus (8)

• Exploring the Charge Density Wave phase of 1$T$-TaSe${}_2$: Mott or Charge-transfer Gap?
• A novel $\sqrt{19}\times \sqrt{19}$ superstructure in epitaxially grown 1T-TaTe${}_2$
• Spin-orbit and exchange proximity couplings in graphene/1T-TaS${}_2$ heterostructure triggered by a charge density wave
• Charge density wave surface reconstruction in a van der Waals layered material
• Orbital textures and evolution of correlated insulating state in monolayer 1T phase transition metal dichalcogenides
• Self-doped flat band and spin-triplet superconductivity in monolayer 1T-TaSe${}_{2-x}$Te${}_x$
• The rich structural, electronic and bonding landscape of 1$T$-type TaTe${}_2$ single-layers
• Strongly Enhanced Charge-Density Waves and Correlated Insulating State in Atomically Thin 1$T$-TaS${}_2$