Electron–phonon coupling contribution on the optical absorption and the dynamic of exciton-polaron in monolayer Transition Metal Dichalcogenides

AbstractThe adoption of high pressure not only reinforces the comprehension of the structure and exotic electronic states of transition metal dichalcogenides (TMDs) but also promotes the discovery of intriguing phenomena. Here, 1T-TaS2 was investigated up to 100 GPa, and re-enhanced superconductivity was found with structural phase transitions. The discovered I4/mmm TaS2 presents strong electron–phonon coupling, revealing a good superconductivity of the nonlayered structure. The P–T phase diagram shows a dome shape centered at ~20 GPa, which is attributed to the distortion of the 1T structure. Accompanied by the transition to nonlayered structure above 44.5 GPa, the superconducting critical temperature shows an increasing trend and reaches ~7 K at the highest studied pressure, presenting superior superconductivity compared to the original layered structure. It is unexpected that the pressure-induced re-enhanced superconductivity was observed in TMDs, and the transition from a superconductor with complicated electron-pairing mechanism to a phonon-mediated superconductor would expand the field of pressure-modified superconductivity.

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Electronic, Thermal Expanding, and Optical Absorption Properties of Transition Metal Dichalcogenides: A First-principles Study

Journal of Wuhan University of Technology-Mater Sci Ed ◽

10.1007/s11595-018-1974-x ◽

2018 ◽

Vol 33 (6) ◽

pp. 1355-1359

Author(s):

Hui Zhang ◽

Yanbin Wu

Keyword(s):

Transition Metal ◽

Optical Absorption ◽

First Principles ◽

Transition Metal Dichalcogenides ◽

Absorption Properties ◽

First Principles Study ◽

Metal Dichalcogenides

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Tunable coupling of terahertz Dirac plasmons and phonons in transition metal dichalcogenide-based van der Waals heterostructures

2D Materials ◽

10.1088/2053-1583/ac37a8 ◽

2021 ◽

Author(s):

Icaro Rodrigues Lavor ◽

Andrey Chaves ◽

Francois M Peeters ◽

Ben Van Duppen

Keyword(s):

Transition Metal ◽

Fermi Energy ◽

Van Der Waals ◽

Transition Metal Dichalcogenides ◽

Transition Metal Dichalcogenide ◽

Phonon Coupling ◽

Van Der Waals Heterostructures ◽

Composition And Structure ◽

Metal Dichalcogenides ◽

Tunable Coupling

Abstract Dirac plasmons in graphene hybridize with phonons of transition metal dichalcogenides (TMDs) when the materials are combined in so-called van der Waals heterostructures (vdWh), thus forming surface plasmon-phonon polaritons (SPPPs). The extend to which these modes are coupled depends on the TMD composition and structure, but also on the plasmons' properties. By performing realistic simulations that account for the contribution of each layer of the vdWh separately, we calculate how the strength of plasmon-phonon coupling depends on the number and composition of TMD layers, on the graphene Fermi energy and the specific phonon mode. From this, we present a semiclassical theory that is capable of capturing all relevant characteristics of the SPPPs. We find that it is possible to realize both strong and ultra-strong coupling regimes by tuning graphene's Fermi energy and changing TMD layer number.

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