Electronic structures, charge transfer, and charge order in twisted transition metal dichalcogenide bilayers

Journal Article · Wed Apr 21 00:00:00 EDT 2021 · Physical Review. B

DOI:https://doi.org/10.1103/physrevb.103.155142· OSTI ID:1852721

Zhang, Yang  ^[1]; Liu, Tongtong ^[1]; Fu, Liang ^[1]

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1. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

Moiré superlattices of transition metal dichalcogenide (TMD) bilayers have been shown to host correlated electronic states, which arise from the interplay of long wavelength moiré potential and long-range Coulomb interaction. Here, we theoretically investigate structural relaxation and single-particle electronic structure of twisted TMD homobilayer. From the large-scale density functional theory calculation and continuum model with layer degrees of freedom, we find that the out-of-plane gating field creates a tunable charge transfer gap at the Dirac point between the first and second moiré valence bands. We further study the charge orders at the fractional band fillings. In the flat band limit, we find from Monte Carlo simulations a series of charge-ordered insulating states at various fillings $$n = \frac{1}{4}, \frac{1}{3}, \frac{1}{2}, \frac{2}{3}, 1$$. Further, we predict that gating field induces a phase transition between different electron crystals at fixed filling $$n = \frac{1}{2}$$ or $$\frac{2}{3}$$. At half-filling $$\textit{n} = 1$$, the ground state is a Mott insulator with electronically driven ferroelectricity. This work demonstrates that TMD homobilayer provides a powerful platform for the investigation of tunable charge transfer insulator and charge orders.

• Research Organization: Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division; Simons Foundation
• Grant/Contract Number: SC0018945
• OSTI ID: 1852721
• Journal Information: Physical Review. B, Vol. 103, Issue 15; ISSN 2469-9950
• Publisher: American Physical Society (APS)
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
36 MATERIALS SCIENCE
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