Mott transition by an impulsive dielectric breakdown

Published online:


The transition of a Mott insulator to metal, the Mott transition, can occur via carrier doping by elemental substitution1, and by photoirradiation, as observed in transition-metal compounds2,3,4 and in organic materials5. Here, we show that the application of a strong electric field can induce a Mott transition by a new pathway, namely through impulsive dielectric breakdown. Irradiation of a terahertz electric-field pulse on an ET-based compound, κ-(ET) 2Cu[N(CN) 2]Br (ET:bis(ethylenedithio)tetrathiafulvalene)6, collapses the original Mott gap of 30 meV with a 0.1 ps time constant after doublon–holon pair productions by quantum tunnelling processes, as indicated by the nonlinear increase of Drude-like low-energy spectral weights. Additionally, we demonstrate metallization using this method is faster than that by a femtosecond laser-pulse irradiation and that the transition dynamics are more electronic and coherent. Thus, strong terahertz-pulse irradiation is an effective approach to achieve a purely electronic Mott transition, enhancing the understanding of its quantum nature.

  • Subscribe to Nature Materials for full access:



Additional access options:

Already a subscriber?  Log in  now or  Register  for online access.


  1. 1.

    , & Metal–insulator transitions. Rev. Mod. Phys. 70, 1039–1263 (1998).

  2. 2.

    et al. Femtosecond structural dynamics in VO2 during an ultrafast solid-solid phase transition. Phys. Rev. Lett. 87, 237401 (2001).

  3. 3.

    et al. Ultrafast optical switching to a metallic state by photoinduced Mott transition in a halogen-bridged Ni-chain compound. Phys. Rev. Lett. 91, 057401 (2003).

  4. 4.

    , , & Sub-picosecond photo-induced melting of a charge-ordered state in a perovskite manganite. Appl. Phys. B 71, 211–215 (2000).

  5. 5.

    et al. Photoinduced metallic state mediated by spin-charge separation in a one-dimensional organic Mott insulator. Phys. Rev. Lett. 98, 037401 (2007).

  6. 6.

    , & Organic Superconductors (Springer, 2007).

  7. 7.

    et al. Organic superconductors-new benchmarks. Science 252, 1501–1508 (1991).

  8. 8.

    et al. Photoinduced transition from Mott insulator to metal in the undoped cuprates Nd2CuO4 and La2CuO4. Phys. Rev. B 83, 125102 (2011).

  9. 9.

    , , & Velocity matching by pulse front tilting for large-area THz-pulse generation. Opt. Express 10, 1161–1166 (2002).

  10. 10.

    , , & Single-cycle terahertz pulses with amplitudes exceeding 1 MV/cm generated by optical rectification in LiNbO3. Appl. Phys. Lett. 98, 091106 (2011).

  11. 11.

    et al. Bi-directional ultrafast electric-field gating of interlayer charge transport in a cuprate superconductor. Nat. Photon. 5, 485–488 (2011).

  12. 12.

    et al. Terahertz-field-induced insulator-to-metal transition in vanadium dioxide metamaterial. Nature 487, 345–348 (2012).

  13. 13.

    , & Resonant and nonresonant control over matter and light by intense terahertz transients. Nat. Photon. 7, 680–690 (2013).

  14. 14.

    , & Terahertz-field-driven sub-picosecond optical switching enabled by large third-order optical nonlinearity in a one-dimensional Mott insulator. Appl. Phys. Lett. 102, 091104 (2013).

  15. 15.

    , , & Ultrafast modulation of polarization amplitude by terahertz fields in electronic-type organic ferroelectrics. Nat. Commun. 4, 2586 (2013).

  16. 16.

    et al. Tunneling breakdown of a strongly correlated insulating state in VO2 induced by intense multiterahertz excitation. Phys. Rev. B 91, 235113 (2015).

  17. 17.

    et al. Terahertz-triggered phase transition and hysteresis narrowing in a nanoantenna patterned vanadium dioxide film. Nano Lett. 15, 5893–5898 (2015).

  18. 18.

    & Ground-state decay rate for the Zener breakdown in band and Mott insulators. Phys. Rev. Lett. 95, 137601 (2005).

  19. 19.

    Nonlinear doublon production in a Mott insulator: Landau–Dykhne method applied to an integrable model. Phys. Rev. B 86, 075148 (2012).

  20. 20.

    et al. A new ambient-pressure organic superconductor, κ-(ET)2Cu[N(CN)2]Br, with the highest transition temperature yet observed (inductive onset Tc = 11.6 K, resistive onset = 12.5 K). Inorg. Chem. 29, 2555–2557 (1990).

  21. 21.

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

  22. 22.

    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).

  23. 23.

    et al. Structure at 20 K of the organic superconductor κ-di[3,4; 3′,4′-bis(ethylenedithio)-2,2′,5,5′-tetrathiafulvalenium] bromo(dicyanamido)cuprate(I), κ-(BEDT-TTF)2Cu[N(CN)2]Br. Acta Cryst. C47, 190–192 (1991).

  24. 24.

    et al. Strain-induced superconductor/insulator transition and field effect in a thin single crystal of molecular conductor. Appl. Phys. Lett. 92, 243508 (2008).

  25. 25.

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

  26. 26.

    et al. Impact ionization in InSb probed by terahertz pump—terahertz probe spectroscopy. Phys. Rev. B 79, 161201(R) (2009).

  27. 27.

    et al. THz-frequency modulation of the Hubbard U in an organic Mott insulator. Phys. Rev. Lett. 115, 187401 (2015).

  28. 28.

    et al. Optical modulation of effective on-site Coulomb energy for the Mott transition in an organic dimer insulator. Phys. Rev. Lett. 103, 066403 (2009).

  29. 29.

    et al. Phonon dynamics and superconductivity in the organic crystal κ-(BEDT-TTF)2Cu[N(CN)2]Br. Physica C 276, 1–8 (1997).

  30. 30.

    , & Role of impact ionization in the thermalization of photoexcited Mott insulators. Phys. Rev. B 90, 235102 (2014).

Download references


We thank R. Shimano, N. Takubo and M. Takenaka for their collaborations in the early stage of this study. This work was partly supported by Grants-in-Aid for Scientific Research from the Japan Society for the Promotion of Science (JSPS) (Project Numbers 25247049, 25247058, 25220709, and 15H03549), Nanotechnology Platform Program (Molecule and Material Synthesis) of the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan, and CREST, Japan Science and Technology Agency (Grant No. JPMJCR1661). H.Yamakawa, T.Morimoto and T.T. were supported by the JSPS through the Program for Leading Graduate Schools (MERIT).

Author information


  1. Department of Advanced Materials Science, University of Tokyo, Chiba 277-8561, Japan

    • H. Yamakawa
    • , T. Miyamoto
    • , T. Morimoto
    • , T. Terashige
    • , H. Yada
    • , N. Kida
    •  & H. Okamoto
  2. Division of Functional Molecular Systems, Research Center of Integrative Molecular Systems (CIMoS), Institute for Molecular Science, Okazaki 444-8585, Japan

    • M. Suda
    •  & H. M. Yamamoto
  3. RIKEN, Wako 351-0198, Japan

    • H. M. Yamamoto
    •  & R. Kato
  4. Department of Applied Physics, University of Tokyo, Bunkyo-ku 113-8656, Japan

    • K. Miyagawa
    •  & K. Kanoda


  1. Search for H. Yamakawa in:

  2. Search for T. Miyamoto in:

  3. Search for T. Morimoto in:

  4. Search for T. Terashige in:

  5. Search for H. Yada in:

  6. Search for N. Kida in:

  7. Search for M. Suda in:

  8. Search for H. M. Yamamoto in:

  9. Search for R. Kato in:

  10. Search for K. Miyagawa in:

  11. Search for K. Kanoda in:

  12. Search for H. Okamoto in:


K.M. and K.K. provided single crystals. M.S., H.M.Y. and R.K. prepared thin single-crystalline samples on diamond substrates. H.Yamakawa measured the steady-state reflectance and transmittance spectra. H.Yamakawa, T.Miyamoto, T.Morimoto, T.T., H.Yada and N.K. constructed the terahertz-pump optical-probe and near-IR-pump optical probe systems. H.Yamakawa and T.Miyamoto performed the measurements. H.O. coordinated the study. H.Yamakawa and H.O. wrote the paper with inputs from all authors.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to H. Okamoto.

Supplementary information

PDF files

  1. 1.

    Supplementary Information

    Supplementary Information