Direct observation of an optically induced charge density wave transition in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>1</mml:mn><mml:mi>T</mml:mi><mml:mtext>−</mml:mtext><mml:msub><mml:mi>TaSe</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math>

Sun, Shuaishuai; Wei, Lingbo; Li, Zhongwen; Cao, Gaoping; Liu, Yu; Lu, W. J.; Sun, Yi‐Yang; Tian, Huanfang; Yang, H. X.; Li, Jianqi

doi:10.1103/physrevb.92.224303

Cited by 47 publications

(28 citation statements)

References 41 publications

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“…Two-dimensional (2D) metallic transition metal dichalcogenides (MTMDCs) such as TiSe 2 1 – 5 , NbSe 2 6 – 9 , TaS 2 10 – 13 , and TaSe 2 14 – 16 , have kindled worldwide research interest due to their rich phase diagrams that include superconductivity, charge-density wave (CDW) and metal-insulator transitions. These intriguing properties are mainly attributed to their reduced dimensionality and the induced quantum confinement effect.…”

Section: Introductionmentioning

confidence: 99%

Two-dimensional metallic tantalum disulfide as a hydrogen evolution catalyst

et al. 2017

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Two-dimensional metallic transition metal dichalcogenides are emerging as prototypes for uncovering fundamental physical phenomena, such as superconductivity and charge-density waves, as well as for engineering-related applications. However, the batch production of such envisioned transition metal dichalcogenides remains challenging, which has hindered the aforementioned explorations. Herein, we fabricate thickness-tunable tantalum disulfide flakes and centimetre-sized ultrathin films on an electrode material of gold foil via a facile chemical vapour deposition route. Through temperature-dependent Raman characterization, we observe the transition from nearly commensurate to commensurate charge-density wave phases with our ultrathin tantalum disulfide flakes. We have obtained high hydrogen evolution reaction efficiency with the as-grown tantalum disulfide flakes directly synthesized on gold foils comparable to traditional platinum catalysts. This work could promote further efforts for exploring new efficient catalysts in the large materials family of metallic transition metal dichalcogenides, as well as exploiting their applications towards more versatile applications.

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Section: Introductionmentioning

confidence: 99%

Two-dimensional metallic tantalum disulfide as a hydrogen evolution catalyst

et al. 2017

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“…Ultrafast electron diffraction has successfully been employed in studies of photo-driven intraplane structural dynamics in TMDs [8,14,[26][27][28]. Recently, Le Guyader et al [29] extended the scope of analysis to include dynamics in stacking order of 1T -TaS 2 .…”

Section: Introductionmentioning

confidence: 99%

Transient three-dimensional structural dynamics in 1T−TaSe2

Grånäs

Weissenrieder

2020

Phys. Rev. B

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We report on thermal and optically driven transitions between the commensurate (C) and incommensurate (IC) charge-density wave (CDW) phases of 1T-TaSe 2. Optical excitation results in suppression of the C-CDW on a subpicosecond timescale. The optically driven C to IC transition involves a short-lived (∼1 ps) unreconstructed phase. Nucleation of an IC phase stacking order is observed already at ∼4 ps following photoexcitation. The short timescales involved in establishing the stacking order implies that the nucleation of the IC phase is influenced by the local geometry of the adjacent layers such that the stacking direction of the C phase determines the stacking direction of the IC phase. From this follows that the nucleation of the IC-CDW is inherently three dimensional (3D). We observe the activation of a coherent shear mode in the optically driven transitions to the transiently stabilized unreconstructed phase. The activation mechanism starts with a rapid lifting of the periodic lattice distortions (PLD) of the Ta sublattice which results in formation of local transient velocity disparities in the Se sublattice. The local differences in Se-phonon amplitudes result in noncompensated shear forces between the layers. This is an example of a multistep coherent launching mechanism. The energy of the optically excited electronic state dissipates energy into modes of the PLD through strong electron-phonon coupling. The rapid suppression of the PLD launches the third step, a coherent vibrational shear mode with low dissipation. The results highlight the importance in considering the 3D nature of the CDWs in the analysis of both structure and dynamics in transition-metal dichalcogenides.

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“…Ultrafast laser excitation can temporarily destroy these thermodynamic ground states and result in quasi-equilibrium states, that is, transient states or metastable phases, which are generally reversible, and revert back to the thermal equilibrium states within 10 −9 to 10 −3 s ( 6 – 11 ), in contrast to the stable photoinduced states in manganite ( 12 , 13 ) and chalcogenide glasses ( 14 ). In recent years, ultrafast transitions and relevant structure dynamics have been extensively investigated in TaS 2 family ( 15 – 18 ). The kinetic process of CDW orders driven by optical excitation revealed that the photoinduced CDW transition follows a distinctly different mechanism from that of the thermally driven equilibrium phase transition.…”

Section: Introductionmentioning

confidence: 99%