Low-energy moiré phonons in twisted bilayer van der Waals heterostructures
Journal Article
·
· Physical Review. B
- Harvard University, Cambridge, MA (United States); SLAC
- Harvard University, Cambridge, MA (United States); SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)
- Harvard University, Cambridge, MA (United States)
We develop a low-energy continuum model for phonons in twisted moiré bilayers, based on a configuration-space approach. In this approach, interatomic force constants are obtained from density functional theory (DFT) calculations of untwisted bilayers with various in-plane shifts. This allows for efficient computation of phonon properties for any small twist angle, while maintaining DFT-level accuracy. Based on this framework, we show how the low-energy phonon modes, including interlayer shearing and layer-breathing modes, vary with the twist angle. As the twist angle decreases, the frequencies of the low-energy modes are reordered and the atomic displacement fields corresponding to phonon eigenmodes break translational symmetry, developing periodicity on the moiré length scale. Here, we demonstrate the capabilities of our model by calculating the phonon properties of three specific structures: bilayer graphene, bilayer molybdenum disulfide (MoS2), and molybdenum diselenide-tungsten diselenide (MoSe2-WSe2).
- Research Organization:
- SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC); National Science Foundation (NSF); Simons Foundation; Army Research Office (ARO)
- Grant/Contract Number:
- AC02-76SF00515; SC0019300
- OSTI ID:
- 1998028
- Journal Information:
- Physical Review. B, Journal Name: Physical Review. B Journal Issue: 14 Vol. 106; ISSN 2469-9950
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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