Ultrafast structural relaxation dynamics of laser-excited graphene: 
<i>Ab initio</i>
 molecular dynamics simulations including electron-phonon interactions

Krylow, Sergej; Hernández, Felipe Valencia; Bauerhenne, Bernd; Garcia, Martín E.

doi:10.1103/physrevb.101.205428

Cited by 13 publications

(6 citation statements)

References 45 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We observe a nonexponential, slow relaxation with characteristic times of the order of tens or hundreds of picoseconds for the particular geometry examined here, depending on the specific combination of TMDs in the heterostructure, varying also with the number of layers and the sharpness of the heterostructure interface. Similar nonexponential energy relaxations have been reported in the relaxation of laser-excited graphene, 55 in low-dimensional (1D and 2D) nonlinear systems due to excitations of intrinsic localized modes (breathers), 56−58 while they are also typically emerging in various glassy materials. 59−61 ■ METHODS Model System.…”

Section: ■ Introductionsupporting

confidence: 64%

Delayed Thermal Relaxation in Lateral Heterostructures of Transition-Metal Dichalcogenides

et al. 2022

View full text Add to dashboard Cite

Recent experimental advances have paved the way for the synthesis of a wide range of transition-metal dichalcogenides (TMDs) and nanoengineering in terms of combining TMDs of different compositions in the same planar structure. Due to numerous suggested optoelectronic applications of these materials, the in-plane heat dissipation of such lateral heterostructures is investigated via molecular dynamics (MD). A broad range of pure and heterostructural TMDs have been considered in terms of the metal (Mo or W) and the chalcogenide (S or Se) combinations. In our MD simulations, we thermally excite the central region of the samples and then allow the excitation to dissipate and reach thermal equilibrium. We observe nonexponential relaxation processes, which are quantified in terms of a characteristic relaxation time. The heat dissipation of bilayer heterostructures is substantially enhanced compared to the single-layer ones. Phonon spectra mismatches among the interfacial and bulk atoms lead to the manifestation of a high barrier for phonon propagation across the boundary of the heterostructure, enhancing the characteristic thermal relaxation times by up to an order of magnitude. The sharpness of the heterostructure interface boundaries plays an important role as well, and it is of major importance when considering applications and the limitations of designing these materials.

show abstract

Section: ■ Introductionsupporting

confidence: 64%

Delayed Thermal Relaxation in Lateral Heterostructures of Transition-Metal Dichalcogenides

et al. 2022

View full text Add to dashboard Cite

show abstract

“…42 were obtained for distorted graphene, which is probably one of the reasons for a significantly higher value of the predicted coupling parameter. They are We note that the electron-phonon coupling parameter calculated by Krylow et al 43 raises with the increase in the electron temperature significantly faster than that predicted by XTANT. The reason for this is that Krylow et al 43 used Eliashberg formalism for the coupling calculations.…”

Section: Resultsmentioning

confidence: 54%

“…2.Electron-ion (electron-phonon) coupling parameter calculated by XTANT10 in a single layer of free-standing graphene monolayer. Top panel: twodimensional coupling parameter, compared with the estimates by Laitinen et al,41 by Pomarico et al,42 and by Krylow et al43 Bottom panel: three-dimensional coupling normalized per thickness of the single layer assumed to be 3.35 Å. also higher than those predicted by other simulations from Refs. 41 and 43.…”

mentioning

confidence: 66%

Response of free-standing graphene monolayer exposed to ultrashort intense XUV pulse from free-electron laser

Medvedev

Noei

Toleikis

et al. 2021

The Journal of Chemical Physics

View full text Add to dashboard Cite

The response of a free-standing graphene monolayer exposed to a few tens of femtoseconds long extreme ultraviolet (XUV) pulse was studied theoretically in order to analyze and compare contributions of various mechanisms to the graphene damage, understood here as a global atomic disintegration. Our simulation results indicate that nonthermal disintegration of the atomic structure is the predominant damage mechanism for a free-standing graphene layer. Only at high absorbed doses, charge-induced disintegration of the graphene structure prevails. We also demonstrate that the progressing damage can be probed by femtosecond optical pulses in the soft UV regime (4 eV photon energy). The achieved quantitative understanding of the damage mechanisms may enable a better control of graphene-based devices when they are exposed to x-ray radiation, as well as an efficient processing of graphene layers with ultrashort intense XUV pulses.

show abstract

“…Our results are in a good agreement with refs 14, 15, and 32 and especially with ref 33, where the attosecond core-level spectroscopy demonstrated that the Raman-inactive A 1 ′ mode is the dominating channel for dissipation of electronic coherence due to stronger coupling to electrons. 50 Note also that in our calculations the acoustic sum rule is not fully fulfilled because we inhibit the long-wavelength dipole-allowed transitions 51,52 by filling the states above the Fermi energy.…”

mentioning

confidence: 94%

Dynamical Phonons Following Electron Relaxation Stages in Photoexcited Graphene

Girotto,

Novko

2023

J. Phys. Chem. Lett.

View full text Add to dashboard Cite

Ultrafast electron−phonon relaxation dynamics in graphene hides many distinct phenomena, such as hot phonon generation, dynamical Kohn anomalies, and phonon decoupling, yet it still remains largely unexplored. Here, we unravel intricate mechanisms governing the vibrational relaxation and phonon dressing in graphene at a highly nonequilibrium state by means of first-principles techniques. We calculate dynamical phonon spectral functions and momentum-resolved line widths for various stages of electron relaxation and find photoinduced phonon hardening, overall increase of relaxation rate and nonadiabaticity, as well as phonon gain. Namely, the initial stage of photoexcitation is found to be governed by strong phonon anomalies of finite-momentum optical modes along with incoherent phonon production. The population inversion state, on the other hand, allows the production of coherent and strongly coupled phonon modes. Our research provides vital insights into the electron−phonon coupling phenomena in graphene and serves as a foundation for exploring nonequilibrium phonon dressing in materials where ordered states and phase transitions can be induced by photoexcitation.

show abstract

Ultrafast structural relaxation dynamics of laser-excited graphene: Ab initio molecular dynamics simulations including electron-phonon interactions

Cited by 13 publications

References 45 publications

Delayed Thermal Relaxation in Lateral Heterostructures of Transition-Metal Dichalcogenides

Delayed Thermal Relaxation in Lateral Heterostructures of Transition-Metal Dichalcogenides

Response of free-standing graphene monolayer exposed to ultrashort intense XUV pulse from free-electron laser

Dynamical Phonons Following Electron Relaxation Stages in Photoexcited Graphene

Contact Info

Product

Resources

About