Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Letter
  • Published:

Non-thermal separation of electronic and structural orders in a persisting charge density wave


The simultaneous ordering of different degrees of freedom in complex materials undergoing spontaneous symmetry-breaking transitions often involves intricate couplings that have remained elusive in phenomena as wide ranging as stripe formation1, unconventional superconductivity1,2,3,4,5,6,7 or colossal magnetoresistance1,8. Ultrafast optical, X-ray and electron pulses can elucidate the microscopic interplay between these orders by probing the electronic and lattice dynamics separately9,10,11,12,13,14,15,16,17, but a simultaneous direct observation of multiple orders on the femtosecond scale has been challenging. Here we show that ultrabroadband terahertz pulses can simultaneously trace the ultrafast evolution of coexisting lattice and electronic orders. For the example of a charge density wave (CDW) in 1T-TiSe2, we demonstrate that two components of the CDW order parameter—excitonic correlations and a periodic lattice distortion (PLD)—respond very differently to 12-fs optical excitation. Even when the excitonic order of the CDW is quenched, the PLD can persist in a coherently excited state. This observation proves that excitonic correlations are not the sole driving force of the CDW transition in 1T-TiSe2, and exemplifies the sort of profound insight that disentangling strongly coupled components of order parameters in the time domain may provide for the understanding of a broad class of phase transitions.

This is a preview of subscription content, access via your institution

Access options

Buy this article

Prices may be subject to local taxes which are calculated during checkout

Figure 1: CDW phase transition in 1T-TiSe2 and its low-energy spectral fingerprint.
Figure 2: Ultrafast photoinduced dynamics of the mid-infrared electronic response.
Figure 3: Terahertz phonon spectrum during ultrafast melting of the electronic order.
Figure 4: CDW amplitude oscillations following a perturbation of the electronic order.

Similar content being viewed by others


  1. Dagotto, E. Complexity in strongly correlated electronic systems. Science 309, 257–262 (2005).

    Article  CAS  Google Scholar 

  2. Torchinsky, D. H., Mahmood, F., Bollinger, A. T., Božović, I. & Gedik, N. Fluctuating charge-density waves in a cuprate superconductor. Nature Mater. 12, 387–391 (2013).

    Article  CAS  Google Scholar 

  3. Sipos, B. et al. From Mott state to superconductivity in 1T-TaS2 . Nature Mater. 7, 960–965 (2008).

    Article  CAS  Google Scholar 

  4. Ghiringhelli, G. et al. Long-range incommensurate charge fluctuations in (Y, Nd)Ba2Cu3O6 + x . Science 337, 821–825 (2012).

    Article  CAS  Google Scholar 

  5. Neto, E. H. d. S. et al. Ubiquitous interplay between charge ordering and high-temperature superconductivity in cuprates. Science 343, 393–396 (2013).

    Article  Google Scholar 

  6. Kiss, T. et al. Charge-order-maximized momentum-dependent superconductivity. Nature Phys. 3, 720–725 (2007).

    Article  CAS  Google Scholar 

  7. Morosan, E. et al. Superconductivity in CuxTiSe2 . Nature Phys. 2, 544–550 (2006).

    Article  CAS  Google Scholar 

  8. Chuang, Y-D., Gromko, A. D., Dessau, D. S., Kimura, T. & Tokura, Y. Fermi surface nesting and nanoscale fluctuating charge/orbital ordering in colossal magnetoresistive oxides. Science 292, 1509–1513 (2001).

    Article  CAS  Google Scholar 

  9. Yusupov, R. et al. Coherent dynamics of macroscopic electronic order through a symmetry breaking transition. Nature Phys. 6, 681–684 (2010).

    Article  CAS  Google Scholar 

  10. Hellmann, S. et al. Time-domain classification of charge-density-wave insulators. Nature Commun. 3, 1069 (2012).

    Article  CAS  Google Scholar 

  11. Kim, K. W. et al. Ultrafast transient generation of spin-density-wave order in the normal state of BaFe2As2 driven by coherent lattice vibrations. Nature Mater. 11, 497–501 (2012).

    Article  CAS  Google Scholar 

  12. Eichberger, M. et al. Snapshots of cooperative atomic motions in the optical suppression of charge density waves. Nature 468, 799–802 (2010).

    Article  CAS  Google Scholar 

  13. Schmitt, F. et al. Transient electronic structure and melting of a charge density wave in TbTe3 . Science 321, 1649–1652 (2008).

    Article  CAS  Google Scholar 

  14. Fausti, D. et al. Light-induced superconductivity in a stripe-ordered cuprate. Science 331, 189–191 (2011).

    Article  CAS  Google Scholar 

  15. Rohwer, T. et al. Collapse of long-range charge order tracked by time-resolved photoemission at high momenta. Nature 471, 490–493 (2011).

    Article  CAS  Google Scholar 

  16. Möhr-Vorobeva, E. et al. Nonthermal melting of a charge density wave in TiSe2 . Phys. Rev. Lett. 107, 036403 (2011).

    Article  Google Scholar 

  17. Wall, S. et al. Ultrafast changes in lattice symmetry probed by coherent phonons. Nature Commun. 3, 721 (2012).

    Article  CAS  Google Scholar 

  18. Weber, F. et al. Electron–phonon coupling and the soft phonon mode in TiSe2 . Phys. Rev. Lett. 107, 266401 (2011).

    Article  CAS  Google Scholar 

  19. Matsunaga, R. et al. Higgs amplitude mode in the BCS superconductors Nb1 − xTixN induced by terahertz pulse excitation. Phys. Rev. Lett. 111, 057002 (2013).

    Article  Google Scholar 

  20. Li, G. et al. Semimetal-to-semimetal charge density wave transition in 1T-TiSe2 . Phys. Rev. Lett. 99, 027404 (2007).

    Article  CAS  Google Scholar 

  21. Holy, J., Woo, K., Klein, M. & Brown, F. Raman and infrared studies of superlattice formation in TiSe2 . Phys. Rev. B 16, 3628–3637 (1977).

    Article  CAS  Google Scholar 

  22. Kampfrath, T., Tanaka, K. & Nelson, K. A. Resonant and nonresonant control over matter and light by intense terahertz transients. Nature Photon. 7, 680–690 (2013).

    Article  CAS  Google Scholar 

  23. Ulbricht, R., Hendry, E., Shan, J., Heinz, T. F. & Bonn, M. Carrier dynamics in semiconductors studied with time-resolved terahertz spectroscopy. Rev. Mod. Phys. 83, 543–586 (2011).

    Article  CAS  Google Scholar 

  24. Cercellier, H. et al. Evidence for an excitonic insulator phase in 1T-TiSe2 . Phys. Rev. Lett. 99, 146403 (2007).

    Article  CAS  Google Scholar 

  25. Kusmartseva, A. F., Sipos, B., Berger, H., Forró, L. & Tutiš, E. Pressure induced superconductivity in pristine 1T-TiSe2 . Phys. Rev. Lett. 103, 236401 (2009).

    Article  CAS  Google Scholar 

  26. Ishioka, J. et al. Chiral charge-density waves. Phys. Rev. Lett. 105, 176401 (2010).

    Article  CAS  Google Scholar 

  27. Kidd, T. E., Miller, T., Chou, M. Y. & Chiang, T-C. Electron–hole coupling and the charge density wave transition in TiSe2 . Phys. Rev. Lett. 88, 226402 (2002).

    Article  CAS  Google Scholar 

  28. Monney, C. et al. Spontaneous exciton condensation in 1T-TiSe2: BCS-like approach. Phys. Rev. B 79, 045116 (2009).

    Article  Google Scholar 

  29. Wezel, J. v., Nahai-Williamson, P. & Saxena, S. S. Exciton–phonon-driven charge density wave in TiSe2 . Phys. Rev. B 81, 165109 (2010).

    Article  Google Scholar 

  30. Huber, R. et al. How many-particle interactions develop after ultrafast excitation of an electron–hole plasma. Nature 414, 286–289 (2001).

    Article  CAS  Google Scholar 

Download references


We thank A. Pashkin and R. Bratschitsch for helpful discussions as well as M. Furthmeier, C. Gradl, K. Groh, T. Riedel and C. Sohrt for technical assistance. Support by the European Research Council through ERC grant 305003 (QUANTUMsubCYCLE) is acknowledged. I.E.P. and L.M. were supported by the European Union’s Seventh Framework Programme (FP7-REGPOT-2012-2013-1) under grant agreement No 316165.

Author information

Authors and Affiliations



M.P., H.D., U.H. and R.H. planned the project; M.P., U.L. and J.-M.M. performed terahertz measurements; M.P., J.D., U.H., J.-M.M., K.R. and R.H. analysed data; K.R. and U.H. provided bulk samples; M.P. prepared thin-film samples; M.P., L.M. and I.E.P. elaborated the theoretical model; M.P., J.D., K.R., I.E.P. and R.H. wrote the paper. All authors contributed to discussions and gave comments on the manuscript.

Corresponding authors

Correspondence to M. Porer or R. Huber.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary Information

Supplementary Information (PDF 1615 kb)

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Porer, M., Leierseder, U., Ménard, JM. et al. Non-thermal separation of electronic and structural orders in a persisting charge density wave. Nature Mater 13, 857–861 (2014).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

This article is cited by


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing