Coexistence of Superconductivity with Enhanced Charge Density Wave Order in the Two-Dimensional Limit of TaSe2

Chao-Sheng Lian, Christoph Heil, Xiaoyu Liu, Chen Si, Feliciano Giustino, Wenhui Duan

Research output: Contribution to journalLetterResearchpeer-review

Abstract

Bulk 2H-TaSe2 is a model charge density wave
(CDW) metal with superconductivity emerging at extremely low
temperature (Tc = 0.1 K). Here, by first-principles calculations
including the explicit calculation of the screened Coulomb
interaction, we demonstrate enhanced superconductivity in the
CDW state of monolayer 1H-TaSe2 observed in recent experi-
ments. Its ground-state 3 × 3 CDW phase features triangular
clustering of Ta atoms and possesses a large electron−phonon
coupling of λ = 0.74, yielding an order of magnitude higher
superconducting Tc compared to the bulk. Upon lowering the
thickness from bulk to monolayer TaSe2, the CDW intensifies with
slightly decreased Fermi-level density of states, while super-
conductivity gets boosted via a largely increased intrinsic
electron−phonon coupling strength, which overcomes both the CDW effect and naturally reinforced Coulomb repulsion.
These results uncover the simultaneously enhanced CDW and superconducting orders in the two-dimensional limit for the first
time and have key implications for other CDW metals like 2H-TaS2.
Original languageEnglish
Article number9b01480
Pages (from-to)4076
Number of pages4081
JournalJournal of Physical Chemistry Letters
Volume10
Issue number14
Publication statusPublished - 5 Jul 2019

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Charge density waves
Superconductivity
superconductivity
Monolayers
Metals
Wave effects
Fermi level
Ground state
metals
emerging
Atoms
conductivity
ground state

Cite this

Coexistence of Superconductivity with Enhanced Charge Density Wave Order in the Two-Dimensional Limit of TaSe2. / Lian, Chao-Sheng; Heil, Christoph; Liu, Xiaoyu; Si, Chen; Giustino, Feliciano; Duan, Wenhui.

In: Journal of Physical Chemistry Letters, Vol. 10, No. 14, 9b01480, 05.07.2019, p. 4076.

Research output: Contribution to journalLetterResearchpeer-review

Lian, Chao-Sheng ; Heil, Christoph ; Liu, Xiaoyu ; Si, Chen ; Giustino, Feliciano ; Duan, Wenhui. / Coexistence of Superconductivity with Enhanced Charge Density Wave Order in the Two-Dimensional Limit of TaSe2. In: Journal of Physical Chemistry Letters. 2019 ; Vol. 10, No. 14. pp. 4076.
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abstract = "Bulk 2H-TaSe2 is a model charge density wave(CDW) metal with superconductivity emerging at extremely lowtemperature (Tc = 0.1 K). Here, by first-principles calculationsincluding the explicit calculation of the screened Coulombinteraction, we demonstrate enhanced superconductivity in theCDW state of monolayer 1H-TaSe2 observed in recent experi-ments. Its ground-state 3 × 3 CDW phase features triangularclustering of Ta atoms and possesses a large electron−phononcoupling of λ = 0.74, yielding an order of magnitude highersuperconducting Tc compared to the bulk. Upon lowering thethickness from bulk to monolayer TaSe2, the CDW intensifies withslightly decreased Fermi-level density of states, while super-conductivity gets boosted via a largely increased intrinsicelectron−phonon coupling strength, which overcomes both the CDW effect and naturally reinforced Coulomb repulsion.These results uncover the simultaneously enhanced CDW and superconducting orders in the two-dimensional limit for the firsttime and have key implications for other CDW metals like 2H-TaS2.",
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T1 - Coexistence of Superconductivity with Enhanced Charge Density Wave Order in the Two-Dimensional Limit of TaSe2

AU - Lian, Chao-Sheng

AU - Heil, Christoph

AU - Liu, Xiaoyu

AU - Si, Chen

AU - Giustino, Feliciano

AU - Duan, Wenhui

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N2 - Bulk 2H-TaSe2 is a model charge density wave(CDW) metal with superconductivity emerging at extremely lowtemperature (Tc = 0.1 K). Here, by first-principles calculationsincluding the explicit calculation of the screened Coulombinteraction, we demonstrate enhanced superconductivity in theCDW state of monolayer 1H-TaSe2 observed in recent experi-ments. Its ground-state 3 × 3 CDW phase features triangularclustering of Ta atoms and possesses a large electron−phononcoupling of λ = 0.74, yielding an order of magnitude highersuperconducting Tc compared to the bulk. Upon lowering thethickness from bulk to monolayer TaSe2, the CDW intensifies withslightly decreased Fermi-level density of states, while super-conductivity gets boosted via a largely increased intrinsicelectron−phonon coupling strength, which overcomes both the CDW effect and naturally reinforced Coulomb repulsion.These results uncover the simultaneously enhanced CDW and superconducting orders in the two-dimensional limit for the firsttime and have key implications for other CDW metals like 2H-TaS2.

AB - Bulk 2H-TaSe2 is a model charge density wave(CDW) metal with superconductivity emerging at extremely lowtemperature (Tc = 0.1 K). Here, by first-principles calculationsincluding the explicit calculation of the screened Coulombinteraction, we demonstrate enhanced superconductivity in theCDW state of monolayer 1H-TaSe2 observed in recent experi-ments. Its ground-state 3 × 3 CDW phase features triangularclustering of Ta atoms and possesses a large electron−phononcoupling of λ = 0.74, yielding an order of magnitude highersuperconducting Tc compared to the bulk. Upon lowering thethickness from bulk to monolayer TaSe2, the CDW intensifies withslightly decreased Fermi-level density of states, while super-conductivity gets boosted via a largely increased intrinsicelectron−phonon coupling strength, which overcomes both the CDW effect and naturally reinforced Coulomb repulsion.These results uncover the simultaneously enhanced CDW and superconducting orders in the two-dimensional limit for the firsttime and have key implications for other CDW metals like 2H-TaS2.

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