Abstract
Ultrafast X-ray scattering is one of the primary tools to track intrinsic crystallographic evolution with atomic accuracy in real time. However, its application to study nonequilibrium structural properties at the two-dimensional limit remains a long-standing challenge due to a significant reduction of diffraction volume and complexity of data analysis. Here, we report femtosecond surface X-ray diffraction in combination with crystallographic model-refinement calculations to quantify the ultrafast structural dynamics of monolayer WSe2 crystals supported on a substrate. We found the absorbed optical photon energy is preferably coupled to the in-plane lattice vibrations within one picosecond whereas the out-of-plane lattice vibration amplitude remains unchanged during the first ten picoseconds. The model-assisted fitting suggests an asymmetric intralayer spacing change upon excitation. The observed nonequilibrium anisotropic structural dynamics agrees with first-principles modelling in both real and momentum space, marking the distinct structural dynamics of monolayer crystals from their bulk counterparts.
This is a preview of subscription content, access via your institution
Access options
Access Nature and 54 other Nature Portfolio journals
Get Nature+, our best-value online-access subscription
$29.99 /Â 30Â days
cancel any time
Subscribe to this journal
Receive 12 print issues and online access
$209.00 per year
only $17.42 per issue
Buy this article
- Purchase on Springer Link
- Instant access to full article PDF
Prices may be subject to local taxes which are calculated during checkout
Similar content being viewed by others
Data availability
The data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request.
References
Novoselov, K. S., Mishchenko, A., Carvalho, A. & Castro Neto, A. H. 2D materials and van der Waals heterostructures. Science 353, aac9439 (2016).
Ajayan, P., Kim, P. & Banerjee, K. Two-dimensional van der Waals materials. Phys. Today 69, 38–44 (September, 2016).
Chernikov, A., Ruppert, C., Hill, H. M., Rigosi, A. F. & Heinz, T. F. Population inversion and giant bandgap renormalization in atomically thin WS2 layers. Nat. Photon. 9, 466–470 (2015).
Langer, F. et al. Lightwave-driven quasiparticle collisions on a subcycle timescale. Nature 533, 225–229 (2016).
Rivera, P. et al. Valley-polarized exciton dynamics in a 2D semiconductor heterostructure. Science 351, 688–691 (2016).
Sun, Y., Wang, R. & Liu, K. Substrate induced changes in atomically thin 2-dimensional semiconductors: Fundamentals, engineering, and applications. Appl. Phys. Rev. 4, 011301 (2017).
Nika, D. L. & Balandin, A. A. Two-dimensional phonon transport in graphene. J. Phys. Condens. Matter 24, 233203 (2012).
Frigge, T. et al. Optically excited structural transition in atomic wires on surfaces at the quantum limit. Nature 544, 207–211 (2017).
Balandin, A. A. et al. Superior thermal conductivity of single-layer graphene. Nano Lett. 8, 902–907 (2008).
Ghosh, S. et al. Dimensional crossover of thermal transport in few-layer graphene. Nat. Mater. 9, 555–558 (2010).
Lee, J. J. et al. Interfacial mode coupling as the origin of the enhancement of T c in FeSe films on SrTiO3. Nature 515, 245–248 (2014).
Chow, C. M. et al. Unusual exciton–phonon Interactions at van der Waals engineered interfaces. Nano Lett. 17, 1194–1199 (2017).
Jin, C. et al. Interlayer electron–phonon coupling in WSe2/hBN heterostructures. Nat. Phys. 13, 127–131 (2017).
Gerber, S. et al. Femtosecond electron–phonon lock-in by photoemission and X-ray free-electron laser. Science 357, 71–75 (2017).
Raman, R. K. et al. Direct observation of optically induced transient structures in graphite using ultrafast electron crystallography. Phys. Rev. Lett. 101, 077401 (2008).
Lin, M.-F. et al. Ultrafast non-radiative dynamics of atomically thin MoSe2. Nat. Commun. 8, 1745 (2017).
Waldecker, L. et al. Momentum-resolved view of electron–phonon coupling in multilayer WSe2. Phys. Rev. Lett. 119, 036803 (2017).
Cremons, D. R., Plemmons, D. A. & Flannigan, D. J. Femtosecond electron imaging of defect-modulated phonon dynamics. Nat. Commun. 7, 11230 (2016).
Cremons, D. R., Plemmons, D. A. & Flannigan, D. J. Defect-mediated phonon dynamics in TaS2 and WSe2. Struct. Dyn. 4, 044019 (2017).
Ruan, C.-Y., Vigliotti, F., Lobastov, V. A., Chen, S. & Zewail, A. H. Ultrafast electron crystallography: transient structures of molecules, surfaces, and phase transitions. Proc. Natl Acad. Sci. USA 101, 1123–1128 (2004).
Ruan, C.-Y., Lobastov, V. A., Vigliotti, F., Chen, S. & Zewail, A. Ultrafast electron crystallography of interfacial water. Science 304, 80–84 (2004).
Mannebach, E. M. et al. Dynamic structural response and deformations of monolayer MoS2 visualized by femtosecond electron diffraction. Nano Lett. 15, 6889–6895 (2015).
Hu, J., Vanacore, G. M., Cepellotti, A., Marzari, N. & Zewail, A. H. Rippling ultrafast dynamics of suspended 2D monolayers, graphene. Proc. Natl Acad. Sci. USA 113, E6555–E6561 (2016).
Mannebach, E. M. et al. Dynamic optical tuning of interlayer interactions in the transition metal dichalcogenides. Nano Lett. 17, 7761–7766 (2017).
Shen, Y. Phase-sensitive sum-frequency spectroscopy. Annu. Rev. Phys. Chem. 64, 129–150 (2013).
Jones, A. M. et al. Excitonic luminescence upconversion in a two-dimensional semiconductor. Nat. Phys. 12, 323–327 (2016).
Mishra, H., Bose, A., Dhar, A. & Bhattacharya, S. Exciton–phonon coupling and band-gap renormalization in monolayer WSe2. Phys. Rev. B 98, 045143 (2018).
Poellmann, C. et al. Resonant internal quantum transitions and femtosecond radiative decay of excitons in monolayer WSe2. Nat. Mater. 14, 889–893 (2015).
Zhu, H. et al. Observation of chiral phonons. Science 359, 579–582 (2018).
Robinson, I. K. & Tweet, D. J. Surface X-ray diffraction. Rep. Prog. Phys. 55, 599–651 (1992).
Brivio, J., Alexander, D. T. L. & Kis, A. Ripples and layers in ultrathin MoS2 membranes. Nano Lett. 11, 5148–5153 (2011).
Meyer, J. C. et al. The structure of suspended graphene sheets. Nature 446, 60–63 (2007).
Shimojo, F. et al. Large nonadiabatic quantum molecular dynamics simulations on parallel computers. Comput. Phys. Commun. 184, 1–8 (2013).
Sadasivam, S., Chan, M. K. & Darancet, P. Theory of thermal relaxation of electrons in semiconductors. Phys. Rev. Lett. 119, 136602 (2017).
Ataca, C., Topsakal, M., Aktürk, E. & Ciraci, S. A comparative study of lattice dynamics of three- and two-dimensional MoS2. J. Phys. Chem. 115, 16354–16361 (2011).
Clark, G. et al. Vapor-transport growth of high optical quality WSe2 monolayers. APL Mater. 2, 101101 (2014).
Jiang, Z. Gixsgui: a matlab toolbox for grazing-incidence X-ray scattering data visualization and reduction, and indexing of buried three-dimensional periodic nanostructured films. J. Appl. Cryst. 48, 917–926 (2015).
Renaud, G. Oxide surfaces and metal/oxide interfaces studied by grazing incidence X-ray scattering. Surf. Sci. Rep. 32, 5–90 (1998).
Mannsfeld, S. C. B., Virkar, A., Reese, C., Toney, M. F. & Bao, Z. Precise structure of pentacene monolayers on amorphous silicon oxide and relation to charge transport. Adv. Mater. 21, 2294–2298 (2009).
Li, Y. et al. Measurement of the optical dielectric function of monolayer transition-metal dichalcogenides: MoS2, MoSe2, WS2, and WSe2. Phys. Rev. B 90, 205422 (2014).
Shimojo, F. et al. A divide-conquer-recombine algorithmic paradigm for large spatiotemporal quantum molecular dynamics simulations. J. Chem. Phys. 140, 18A529 (2014).
Hohenberg, P. & Kohn, W. Inhomogeneous electron gas. Phys. Rev. 136, B864–B871 (1964).
Kohn, W. & Sham, L. Self-consistent equations including exchange and correlation effects. Phys. Rev. 140, A1133–A1138 (1965).
Perdew, J. P., Burke, K. & Ernzerhof, M. Generalized gradient approximation made simple. Phys. Rev. Lett. 77, 3865–3868 (1996).
Blöchl, P. E. Projector augmented-wave method. Phys. Rev. B 50, 17953–17979 (1994).
Grimme, S. Semiempirical GGA-type density functional constructed with a long-range dispersion correction. J. Comput. Chem. 27, 1787–1799 (2006).
Acknowledgements
I.-C.T., Q.Z., K.S., G.C., X.X. and H.W. acknowledge support from the Department of Energy, Office of Science, Office of Basic Energy Sciences, Materials Sciences and Engineering Division, under contract no. DE-SC0012509. A.K., H.K., A.N., F.S., R.K.K. and P.V. acknowledge support of the Computational Materials Sciences Program funded by the US Department of Energy, Office of Science, Basic Energy Sciences, under Award Number DE-SC0014607. E.M.M., C.N., A.M.L. and T.F.H. acknowledge support by the Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division, under contract DE-AC02-76SF00515. F.E. gratefully acknowledges grant LPDS 2013-13 from the German National Academy of Sciences Leopoldina. NAQMD simulations were performed at the Argonne Leadership Computing Facility under the Department of Energy, the Innovative and Novel Computational Impact on Theory and Experiment Program and at the Center for High Performance Computing of the University of Southern California. Use of the Linac Coherent Light Source, SLAC National Accelerator Laboratory, is supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences under contract no. DE-AC02-76SF00515. Work at the Advanced Photon Source and the Center for Nanoscale Materials was supported by the US Department of Energy, Office of Science, under contract no. DE-AC02-06CH11357. S.Sa. was supported by Laboratory Directed Research and Development (LDRD) funding from Argonne National Laboratory.
Author information
Authors and Affiliations
Contributions
I.C.T., H.Z., Q.Z., K.S., E.M., C.N., F.E., D.Z., J.G., M.K., S.Song, S.N., T.H., X.X., A.L. and H.W. performed the experiments. A.K. H.K., F.S., R.K., R.V., A.N., S. Sadavisam and P.D. performed first-principles calculations. K.S., G.C. and X.X. made samples. I.C.T. and H.W. wrote the manuscript with contributions from all authors. H.W. and X.X. conceived this study.
Corresponding author
Ethics declarations
Competing interests
The authors declare no competing interests.
Additional information
Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Supplementary information
Supplementary Information
Supplementary notes and figures.
Rights and permissions
About this article
Cite this article
Tung, IC., Krishnamoorthy, A., Sadasivam, S. et al. Anisotropic structural dynamics of monolayer crystals revealed by femtosecond surface X-ray scattering. Nat. Photonics 13, 425–430 (2019). https://doi.org/10.1038/s41566-019-0387-5
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1038/s41566-019-0387-5
This article is cited by
-
Three-stage ultrafast demagnetization dynamics in a monolayer ferromagnet
Nature Communications (2024)