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Nonlinear charge oscillation driven by a single-cycle light field in an organic superconductor

Nature Photonicsvolume 12pages474478 (2018) | Download Citation


Application of an intense light field to solids produces enormous and ultrafast nonlinear phenomena such as high-harmonic generation1,2 and attosecond charge dynamics3,4. These are distinct from conventional photonics. However, the main targets for investigation have been limited to insulators and semiconductors, although theoretical approaches have also been developed for correlated metals and superconductors5. Here, in a layered organic superconductor, a nonlinear charge oscillation driven by a nearly single-cycle strong electric field of >10 MV cm−1 is observed as a stimulated emission. The charge oscillation is different from a linear response and ascribed to a polar charge oscillation with a period of 6 fs. This nonlinear polar charge oscillation is enhanced by critical fluctuations near a superconducting transition temperature and a critical end-point of first-order Mott transitions. Its observation on an ultrafast timescale of 10 fs clarifies that Coulomb repulsion plays an essential role in the superconductivity of organic superconductors.

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  1. 1.

    Schubert, O. et al. Sub-cycle control of terahertz high-harmonic generation by dynamical Bloch oscillations. Nat. Photon. 8, 119–123 (2014).

  2. 2.

    Luu, T. T. et al. Extreme ultraviolet high-harmonic spectroscopy of solids. Nature 521, 498–502 (2015).

  3. 3.

    Schultze, M. et al. Attosecond band-gap dynamics in silicon. Science 346, 1348–1352 (2014).

  4. 4.

    Lucchini, M. et al. Attosecond dynamical Franz–Keldysh effect in polycrystalline diamond. Science 353, 916–919 (2016).

  5. 5.

    Aoki, H. et al. Nonequilibrium dynamical mean-field theory and its applications. Rev. Mod. Phys. 86, 779–837 (2014).

  6. 6.

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

  7. 7.

    Hase, M., Kitajima, M., Constantinescu, A. M. & Petek, H. The birth of a quasiparticle in silicon observed in time–frequency space. Nature 426, 51–54 (2003).

  8. 8.

    Basov, D. N. et al. Electrodynamics of correlated electron materials. Rev. Mod. Phys. 83, 471–541 (2011).

  9. 9.

    Schoenlein, R. W., Lin, W. Z., Fujimoto, J. G. & Eesley, G. L. Femtosecond studies of nonequilibrium electronic processes in metals. Phys. Rev. Lett. 58, 1680–1683 (1987).

  10. 10.

    Han, S. G. et al. Femtosecond optical detection of quasiparticle dynamics in high-T c YBa2Cu3O7−δ superconducting thin films. Phys. Rev. Lett. 65, 2708–2711 (1990).

  11. 11.

    Demsar, J. et al. Superconducting gap Δ c, the pseudogap Δ p, and pair fluctuations above T c in overdoped Y1 xCaxBa2Cu3O7 δ from femtosecond time-domain spectroscopy. Phys. Rev. Lett. 82, 4918–4921 (1999).

  12. 12.

    Kaindl, R. A. et al. Ultrafast mid-infrared response of YBa2Cu3O7 δ. Science 287, 470–473 (2000).

  13. 13.

    Toda, Y., Mertelj, T., Naito, T. & Mihailovic, D. Femtosecond carrier relaxation dynamics and photoinduced phase separation in κ-(BEDT-TTF)2Cu[N(CN)2]X (X = Br, Cl). Phys. Rev. Lett. 107, 227002 (2011).

  14. 14.

    Giannetti, C. et al. Ultrafast optical spectroscopy of strongly correlated materials and high-temperature superconductors: a non-equilibrium approach. Adv. Phys. 65, 58–238 (2016).

  15. 15.

    Ishikawa, T. et al. Optical freezing of charge motion in an organic conductor. Nat. Commun. 5, 5528 (2014).

  16. 16.

    Fukaya, R. et al. Ultrafast electronic state conversion at room temperature utilizing hidden state in cuprate ladder system. Nat. Commun. 6, 8519 (2015).

  17. 17.

    Matsunaga, R. et al. Light-induced collective pseudospin precession resonating with Higgs mode in a superconductor. Science 345, 1145–1149 (2014).

  18. 18.

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

  19. 19.

    Imada, M., Fujimori, A. & Tokura, Y. Metal–insulator transitions. Rev. Mod. Phys. 70, 1039–1263 (1998).

  20. 20.

    Kanoda, K. Recent progress in NMR studies on organic conductors. Hyperfine Interact. 104, 235–249 (1997).

  21. 21.

    Kagawa, F., Miyagawa, K. & Kanoda, K. Unconventional critical behavior in a quasi-two-dimensional organic conductor. Nature 436, 534–537 (2005).

  22. 22.

    Powell, B. J. & McKenzie, R. H. Strong electronic correlations in superconducting organic charge transfer salts. J. Phys. Condens. Matter 18, R827–R866 (2006).

  23. 23.

    Terletska, H., Vučičević, J., Tanasković, D. & Dobrosavljević, V. Quantum critical transport near the Mott transition. Phys. Rev. Lett. 107, 026401 (2011).

  24. 24.

    Sasaki, T. et al. Electronic correlation in the infrared optical properties of the quasi-two-dimensional κ-type BEDT-TTF dimer system. Phys. Rev. B 69, 064508 (2004).

  25. 25.

    Faltermeier, D. et al. Bandwidth-controlled Mott transition in κ-(BEDT-TTF)2Cu[N(CN)2]BrxCl1−x: optical studies of localized charge excitations. Phys. Rev. B 76, 165113 (2007).

  26. 26.

    Dressel, M. & Drichiko, N. Optical properties of two-dimensional organic conductors: signatures of charge ordering and correlation effects. Chem. Rev. 104, 5689–5715 (2004).

  27. 27.

    Yamamoto, H. M. et al. A strained organic field-effect transistor with a gate-tunable superconducting channel. Nat. Commun. 4, 2379 (2013).

  28. 28.

    Sekine, A., Nasu, J. & Ishihara, S. Polar charge fluctuation and superconductivity in organic conductors. Phys. Rev. B 87, 085133 (2013).

  29. 29.

    Watanabe, H., Seo, H. & Yunoki, S. Phase competition and superconductivity in κ-(BEDT-TTF)2X: importance of intermolecular Coulomb interactions. J. Phys. Soc. Jpn 86, 033703 (2017).

  30. 30.

    Kawakami, Y. et al. Polarization selectivity of charge localization induced by a 7-fs nearly single-cycle lightfield in an organic metal. Phys. Rev. B 95, 201105(R) (2017).

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This work was supported by the Japan Science and Technology Agency (Core Research for Evolutional Science and Technology (CREST: Elucidation of elementary dynamics of photoinduced phase transition by using advanced ultrashort light pulses) and Exploratory Research for Advanced Technology (ERATO: JPMJER1301)) and the Japan Society for the Promotion of Science (grant numbers JP15H02100, JP23244062, JP16K13814, JP17K14317, JP26887003, JP16K05459, JP25287080, JP26287070, JP17H02916 and JP16H04140). Part of the work was conducted in the Equipment Development Center (Institute for Molecular Science), supported by the Nanotechnology Platform Program (Molecule and Material Synthesis) of the Ministry of Education, Culture, Sports, Science and Technology, Japan.

Author information


  1. Department of Physics, Tohoku University, Sendai, Japan

    • Y. Kawakami
    • , T. Amano
    • , Y. Yoneyama
    • , Y. Akamine
    • , H. Itoh
    • , S. Ishihara
    •  & S. Iwai
  2. Institute for Molecular Science, Okazaki, Japan

    • G. Kawaguchi
    •  & H. M. Yamamoto
  3. Department of Applied Physics, Nagoya University, Nagoya, Japan

    • H. Kishida
  4. Institute for Materials Research, Tohoku University, Sendai, Japan

    • K. Itoh
    •  & T. Sasaki
  5. Department of Physics, Chuo University, Tokyo, Japan

    • Y. Tanaka
    •  & K. Yonemitsu


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Y.K., T.A., Y.Y., Y.A., H.I. and S.Iw. developed the 6 fs light source, carried out the transient reflectivity/transmittance measurements using the 6 fs pulse and, with contributions from H.K., analysed the data. G.K. and H.M.Y. performed the synthesis and characterization of the thin film. K.I., H.K. and T.S. performed the synthesis and characterization of the single crystal. S.Is., Y.T. and K.Y. made theoretical considerations and calculations. S.Iw. devised all of the experiments. Y.K., K.Y. and S.Iw. wrote the paper after discussions with all co-authors.

Competing interests

The authors declare no competing interests.

Corresponding author

Correspondence to S. Iwai.

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