Attosecond screening dynamics mediated by electron localization in transition metals

Abstract

Transition metals, with their densely confined and strongly coupled valence electrons, are key constituents of many materials with unconventional properties1, such as high-temperature superconductors, Mott insulators and transition metal dichalcogenides2. Strong interaction offers a fast and efficient lever to manipulate electron properties with light, creating promising potential for next-generation electronics3,4,5,6. However, the underlying dynamics is a hard-to-understand, fast and intricate interplay of polarization and screening effects, which are hidden below the femtosecond timescale of electronic thermalization that follows photoexcitation7. Here, we investigate the many-body electron dynamics in transition metals before thermalization sets in. We combine the sensitivity of intra-shell transitions to screening effects8 with attosecond time resolution to uncover the interplay of photo-absorption and screening. First-principles time-dependent calculations allow us to assign our experimental observations to ultrafast electronic localization on d orbitals. The latter modifies the electronic structure as well as the collective dynamic response of the system on a timescale much faster than the light-field cycle. Our results demonstrate a possibility for steering the electronic properties of solids before electron thermalization. We anticipate that our study may facilitate further investigations of electronic phase transitions, laser–metal interactions and photo-absorption in correlated-electron systems on their natural timescales.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

Fig. 1: Attosecond transient absorption spectroscopy.
Fig. 2: Experimental pump–probe results.
Fig. 3: Ab initio calculation results.
Fig. 4: Real-time and real-space theoretical investigation of the laser-driven microscopic electron dynamics in Ti.

Data availability

The data that support the findings of this study are available via https://doi.org/10.3929/ethz-b-000345468 or from the corresponding author upon reasonable request.

Code availability

The Octopus code for TDDFT is available at https://octopus-code.org.

References

  1. 1.

    Kotliar, G. & Vollhardt, D. Strongly correlated materials: insights from dynamical mean-field theory. Phys. Today 57, 53–59 (2004).

  2. 2.

    Manzeli, S., Ovchinnikov, D., Pasquier, D., Yazyev, O. V. & Kis, A. 2D transition metal dichalcogenides. Nat. Rev. Mater. 2, 17033 (2017).

  3. 3.

    Nasu, K. Photoinduced Phase Transitions (World Scientific, 2004).

  4. 4.

    Wegkamp, D. et al. Instantaneous band gap collapse in photoexcited monoclinic VO2 due to photocarrier doping. Phys. Rev. Lett. 113, 216401 (2014).

  5. 5.

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

  6. 6.

    Zhou, Y. & Ramanathan, S. Correlated electron materials and field effect transistors for logic: a review. Crit. Rev. Solid State Mater. Sci. 38, 286–317 (2013).

  7. 7.

    Bauer, M., Marienfeld, A. & Aeschlimann, M. Hot electron lifetimes in metals probed by time-resolved two-photon photoemission. Prog. Surf. Sci. 90, 319–376 (2015).

  8. 8.

    Amusia, M. Y. & Connerade, J.-P. The theory of collective motion probed by light. Rep. Prog. Phys. 63, 41–70 (2000).

  9. 9.

    Schultze, M. et al. Controlling dielectrics with the electric field of light. Nature 493, 75–78 (2013).

  10. 10.

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

  11. 11.

    Mashiko, H., Oguri, K., Yamaguchi, T., Suda, A. & Gotoh, H. Petahertz optical drive with wide-bandgap semiconductor. Nat. Phys. 12, 741–745 (2016).

  12. 12.

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

  13. 13.

    Moulet, A. et al. Soft X-ray excitonics. Science 357, 1134–1138 (2017).

  14. 14.

    Schlaepfer, F. et al. Attosecond optical-field-enhanced carrier injection into the GaAs conduction band. Nat. Phys. 14, 560–564 (2018).

  15. 15.

    Jager, M. F. et al. Tracking the insulator-to-metal phase transition in VO2 with few-femtosecond extreme UV transient absorption spectroscopy. Proc. Natl Acad. Sci. USA 114, 9558–9563 (2017).

  16. 16.

    Akama, T. et al. Schottky solar cell using few-layered transition metal dichalcogenides toward large-scale fabrication of semitransparent and flexible power generator. Sci. Rep. 7, 11967 (2017).

  17. 17.

    Cavalieri, A. L. et al. Attosecond spectroscopy in condensed matter. Nature 449, 1029–1032 (2007).

  18. 18.

    Tao, Z. et al. Direct time-domain observation of attosecond final-state lifetimes in photoemission from solids. Science 353, 62–67 (2016).

  19. 19.

    Kasmi, L. et al. Effective mass effect in attosecond electron transport. Optica 4, 1492 (2017).

  20. 20.

    Ambrosio, M. J. & Thumm, U. Electronic structure effects in spatiotemporally resolved photoemission interferograms of copper surfaces. Phys. Rev. A 96, 051403 (2017).

  21. 21.

    Lucchini, M. et al. Light–matter interaction at surfaces in the spatiotemporal limit of macroscopic models. Phys. Rev. Lett. 115, 137401 (2015).

  22. 22.

    Swoboda, M. et al. Intensity dependence of laser-assisted attosecond photoionization spectra. Laser Phys. 19, 1591–1599 (2009).

  23. 23.

    Cho, B. I. et al. Electronic structure of warm dense copper studied by ultrafast X-ray absorption spectroscopy. Phys. Rev. Lett. 106, 167601 (2011).

  24. 24.

    Dorchies, F. et al. Time evolution of electron structure in femtosecond heated warm dense molybdenum. Phys. Rev. B 92, 144201 (2015).

  25. 25.

    Principi, E. et al. Free electron laser-driven ultrafast rearrangement of the electronic structure in Ti. Struct. Dyn. 3, 023604 (2016).

  26. 26.

    Williams, G. O. et al. Tracking the ultrafast XUV optical properties of X-ray free-electron-laser heated matter with high-order harmonics. Phys. Rev. A 97, 023414 (2018).

  27. 27.

    Locher, R. et al. Versatile attosecond beamline in a two-foci configuration for simultaneous time-resolved measurements. Rev. Sci. Instrum. 85, 013113 (2014).

  28. 28.

    Marques, M. A. L., Maitra, N. T., Nogueira, F. M. S., Gross, E. K. U. & Rubio, A. Fundamentals of Time-Dependent Density Functional Theory 837 (Springer, 2012).

  29. 29.

    Sommer, A. et al. Attosecond nonlinear polarization and light–matter energy transfer in solids. Nature 534, 86–90 (2016).

  30. 30.

    Krasovskii, E. & Schattke, W. Local field effects in optical excitations of semicore electrons. Phys. Rev. B 60, 16251–16254 (1999).

  31. 31.

    Fuggle, J. C. & Mårtensson, N. Core-level binding energies in metals. J. Electron Spectros. Relat. Phenom. 21, 275–281 (1980).

  32. 32.

    Connerade, J. P. in Giant Resonances in Atoms, Molecules, and Solids Vol. 151 (eds Connerade, J. P., Esteva, J. M. & Karnatak, R. C.) 3–23 (Springer, 1987).

  33. 33.

    Ankudinov, A. L., Nesvizhskii, A. I. & Rehr, J. J. Dynamic screening effects in X-ray absorption spectra. Phys. Rev. B 67, 115120 (2003).

  34. 34.

    Sato, S. A. et al. Role of intraband transitions in photocarrier generation. Phys. Rev. B 98, 035202 (2018).

  35. 35.

    Sato, S. A., Yabana, K., Shinohara, Y., Otobe, T. & Bertsch, G. F. Numerical pump–probe experiments of laser-excited silicon in nonequilibrium phase. Phys. Rev. B 89, 064304 (2014).

  36. 36.

    Bévillon, E., Colombier, J. P., Recoules, V. & Stoian, R. Free-electron properties of metals under ultrafast laser-induced electron–phonon nonequilibrium: a first-principles study. Phys. Rev. B 89, 115117 (2014).

  37. 37.

    Anisimov, V. I. & Gunnarsson, O. Density-functional calculation of effective Coulomb interactions in metals. Phys. Rev. B 43, 7570–7574 (1991).

  38. 38.

    Bévillon, E. et al. Ultrafast switching of surface plasmonic conditions in nonplasmonic metals. Phys. Rev. B 93, 165416 (2016).

  39. 39.

    Winter, J., Rapp, S., Schmidt, M. & Huber, H. P. Ultrafast laser processing of copper: a comparative study of experimental and simulated transient optical properties. Appl. Surf. Sci. 417, 2–15 (2017).

  40. 40.

    Hentschel, M. et al. Attosecond metrology. Nature 414, 509–513 (2001).

  41. 41.

    Itatani, J. et al. Attosecond streak camera. Phys. Rev. Lett. 88, 173903 (2002).

  42. 42.

    Perdew, J. P. & Wang, Y. Accurate and simple analytic representation of the electron-gas correlation energy. Phys. Rev. B 45, 13244–13249 (1992).

  43. 43.

    Troullier, N. & Martins, J. L. Efficient pseudopotentials for plane-wave calculations. Phys. Rev. B 43, 1991–1997 (1991).

  44. 44.

    Reis, C., Pacheco, M. & Martins, J. First-principles norm-conserving pseudopotential with explicit incorporation of semicore states. Phys. Rev. B 68, 155111 (2003).

  45. 45.

    Andrade, X. et al. Real-space grids and the Octopus code as tools for the development of new simulation approaches for electronic systems. Phys. Chem. Chem. Phys. 17, 31371–31396 (2015).

  46. 46.

    Sato, S. A., Shinohara, Y., Otobe, T. & Yabana, K. Dielectric response of laser-excited silicon at finite electron temperature. Phys. Rev. B 90, 174303 (2014).

Download references

Acknowledgements

The authors acknowledge discussions with E. Krasovskii. S.A.S. and A.R. thank M. J. T. Oliveira for helping with the generation of a transferable pseudopotential for Ti, dealing with semicore electrons. This work was supported by the National Center of Competence in Research – Molecular Ultrafast Science and Technology (NCCR MUST) funded by the Swiss National Science Foundation. The authors acknowledge financial support from the European Research Council (ERC-2015-AdG-694097) and the European Union’s Horizon 2020 Research and Innovation programme under grant agreement no. 676580 (NOMAD). S.A.S. acknowledges support from the Alexander von Humboldt Foundation.

Author information

M.V., S.A.S., L.G., A.R. and U.K. supervised the study. M.V., F.S., N.H., L.K. and M.L. conducted the experiments. M.V. and F.S. analysed the experimental data. S.A.S. and A.R. developed the theoretical modelling. All authors were involved in the interpretation of data and contributed to the final manuscript.

Correspondence to M. Volkov.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Peer review information: Nature Physics thanks Pablo Maldonado and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Supplementary Information

Supplementary Information

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark