Attosecond screening dynamics mediated by electron-localization in transition metals

Nature Physics 15, 1145 - 1149 (2019)

Attosecond screening dynamics mediated by electron-localization in transition metals

M. Volkov, S. A. Sato, F. Schlaepfer, L. Kasmi, N. Hartmann, M. Lucchini, L. Gallmann, A. Rubio, U. Keller

Transition metals with their densely confined and strongly coupled valence electrons are key constituents of many materials with unconventional properties, such as high-Tc superconductors, Mott insulators and transition-metal dichalcogenides. Strong electron interaction offers a fast and efficient lever to manipulate their properties with light, creating promising potential for next-generation electronics. However, the underlying dynamics is a fast and intricate interplay of polarization and screening effects, which is poorly understood. It is hidden below the femtosecond timescale of electronic thermalization, which follows the light-induced excitation. 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 effects 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 whole 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 prior to electron thermalization, suggesting that the ultimate speed of electronic phase transitions is limited only by the duration of the controlling laser pulse. Furthermore, external control of the local electronic density serves as a fine tool for testing state-of-the art models of electron-electron interactions. We anticipate our study to facilitate further investigations of electronic phase transitions, laser-metal interactions and photo-absorption in correlated electron systems on its natural timescale.

Additional Information

Preprint - 2.9 MB
We thank Prof. E. Krasovskii for valuable discussions. 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. We acknowledge financial support from the European Research Council (ERC-2015-AdG-694097), and the European Union's Horizon 2020 Research and Innovation program under Grant Agreements no. 676580 (NOMAD). S. A. S. acknowledges support by Alexander von Humboldt Foundation.

Related Projects

Related Research Areas