Phase ordering of charge density waves traced by ultrafast low-energy electron diffraction

Vogelgesang, Simon; Storeck, Gero; Horstmann, Jan; Diekmann, Theo; Sivis, Murat; Schramm, Sebastian; Roßnagel, Kai; Schäfer, Sascha; Ropers, Claus

doi:10.1038/nphys4309

Cited by 158 publications

(213 citation statements)

References 61 publications

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“…8 shows the amplitudes of the oscillation versus the domain volumes, which is fitted using a linear behavior, A d = aV + b. We conclude that the magnitude of the coherently ex-Laulhé et al [10] Vogelgesang et al [11] this cited amplitude mode decreases as the I-CDW domains get larger.…”

Section: Resultsmentioning

confidence: 99%

“…Table II shows the estimated density of absorbed photons for our experiment and for Refs. [10,11]. Even though the photon energy in the experiment from Ref.…”

Section: Discussionmentioning

confidence: 99%

“…Previous experiments have shown that the correlation length of the photoinduced I phase increases with time, up to several nanoseconds after the transition is triggered by a pump pulse [10,11]. According to our current understanding of this process, initially several independent regions exhibiting I-CDW phase modulations nucleate and grow from the excited NC phase.…”

Section: Introductionmentioning

confidence: 96%

“…A photon energy of 7 keV is selected by means of a Si(111) double monochromator, leading to a high momentum resolution of 3.5 10 −4Å−1 . The latter value is two orders of magnitude finer than with time-resolved electron diffraction [11,15]. This configuration was chosen for the reciprocal space mapping since the dynamics of domain growth occur on timescales of hundreds of picoseconds, and a very good momentum resolution and high flux are necessary.…”

Section: Experimental Methodsmentioning

confidence: 99%

“…The satellite peak width can be determined in various directions and used to derive the correlation lengths along those directions. Previous experiments using electron diffraction or point detectors have been able to study the intensity and the correlation length of the CDW only in the in-plane directions [10,11,15].…”

Section: Introductionmentioning

confidence: 99%

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Domain-size effects on the dynamics of a charge density wave in 1T−TaS2

et al. 2017

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Recent experiments have shown that the high temperature incommensurate (I) charge density wave (CDW) phase of 1T-TaS2 can be photoinduced from the lower temperature, nearly commensurate (NC) CDW state. Here we report a time-resolved x-ray diffraction study of the growth process of the photoinduced I-CDW domains. The layered nature of the material results in a marked anisotropy in the size of the photoinduced domains of the I-phase. These are found to grow self-similarly, their shape remaining unchanged throughout the growth process. The photoinduced dynamics of the newly formed I-CDW phase was probed at various stages of the growth process using a double pump scheme, where a first pump creates I-CDW domains and a second pump excites the newly formed I-CDW state. We observe larger magnitudes of the coherently excited I-CDW amplitude mode in smaller domains, which suggests that the incommensurate lattice distortion is less stable for smaller domain sizes.

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Section: Resultsmentioning

confidence: 99%

“…Table II shows the estimated density of absorbed photons for our experiment and for Refs. [10,11]. Even though the photon energy in the experiment from Ref.…”

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

Section: Experimental Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Domain-size effects on the dynamics of a charge density wave in 1T−TaS2

et al. 2017

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Indirect Exciton–Phonon Dynamics in MoS₂ Revealed by Ultrafast Electron Diffraction

Xiang

Matilde

et al. 2023

Adv Funct Materials

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Transition metal dichalcogenides layered nano‐crystals are emerging as promising candidates for next‐generation optoelectronic and quantum devices. In such systems, the interaction between excitonic states and atomic vibrations is crucial for many fundamental properties, such as carrier mobilities, quantum coherence loss, and heat dissipation. In particular, to fully exploit their valley‐selective excitations, one has to understand the many‐body exciton physics of zone‐edge states. So far, theoretical and experimental studies have mainly focused on the exciton–phonon dynamics in high‐energy direct excitons involving zone‐center phonons. Here, ultrafast electron diffraction and ab initio calculations are used to investigate the many‐body structural dynamics following nearly‐ resonant excitation of low‐energy indirect excitons in MoS2. By exploiting the large momentum carried by scattered electrons, the excitation of in‐plane K‐ and Q‐ phonon modes are identified with 𝑬′ symmetry as key for the stabilization of indirect excitons generated via near‐infrared light at 1.55 eV, and light is shed on the role of phonon anharmonicity and the ensuing structural evolution of the MoS2 crystal lattice. The results highlight the strong selectivity of phononic excitations directly associated with the specific indirect‐ exciton nature of the wavelength‐dependent electronic transitions triggered in the system.

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Structure and Nonequilibrium Heat‐Transfer of a Physisorbed Molecular Layer on Graphene

Wit

Bunjes

Wenderoth

et al. 2020

Adv Materials Inter

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The structure of a physisorbed sub-monolayer of 1,2-bis(4-pyridyl)ethylene (bpe) on epitaxial graphene is investigated by Low-Energy Electron Diffraction and Scanning Tunneling Microscopy. Additionally, non-equilibrium heat-transfer between bpe and the surface is studied by Ultrafast Low-Energy Electron Diffraction. Bpe arranges in an oblique unit cell which is not commensurate with the substrate. Six different rotational and/or mirror domains, in which the molecular unit cell is rotated by 28±0.1 with respect to the graphene surface, are identified. The molecules are weakly physisorbed, as evidenced by the fact that they readily desorb at room temperature. At liquid nitrogen temperature, however, the layers are stable and time-resolved experiments can be performed. The temperature changes of the molecules and the surface can be measured independently through the Debye-Waller factor of their individual diffraction features. Thus, the heat flow between bpe and the surface can be monitored on a picosecond timescale. The time-resolved measurements, in combination with model simulations, show the existence of three relevant thermal barriers between the different layers. The thermal boundary resistance between the molecular layer and graphene was found to be 2±1•10-8 K m 2 W-1. Received: ((will be filled in by the editorial staff)) Revised: ((will be filled in by the editorial staff))

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Phase ordering of charge density waves traced by ultrafast low-energy electron diffraction

Cited by 158 publications

References 61 publications

Domain-size effects on the dynamics of a charge density wave in 1T−TaS2

Domain-size effects on the dynamics of a charge density wave in 1T−TaS2

Indirect Exciton–Phonon Dynamics in MoS₂ Revealed by Ultrafast Electron Diffraction

Structure and Nonequilibrium Heat‐Transfer of a Physisorbed Molecular Layer on Graphene

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Phase ordering of charge density waves traced by ultrafast low-energy electron diffraction

Cited by 158 publications

References 61 publications

Domain-size effects on the dynamics of a charge density wave in 1T−TaS2

Domain-size effects on the dynamics of a charge density wave in 1T−TaS2

Indirect Exciton–Phonon Dynamics in MoS2 Revealed by Ultrafast Electron Diffraction

Structure and Nonequilibrium Heat‐Transfer of a Physisorbed Molecular Layer on Graphene

Contact Info

Product

Resources

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Indirect Exciton–Phonon Dynamics in MoS₂ Revealed by Ultrafast Electron Diffraction