Ultrafast multi-cycle terahertz measurements of the electrical conductivity in strongly excited solids

• Published in: Nature communications Vol. 12; no. 1; p. 1638
• Main Authors: Chen, Z., Curry, C. B., Zhang, R., Treffert, F., Stojanovic, N., Toleikis, S., Pan, R., Gauthier, M., Zapolnova, E., Seipp, L. E., Weinmann, A., Mo, M. Z., Kim, J. B., Witte, B. B. L., Bajt, S., Usenko, S., Soufli, R., Pardini, T., Hau-Riege, S., Burcklen, C., Schein, J., Redmer, R., Tsui, Y. Y., Ofori-Okai, B. K., Glenzer, S. H.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 12.03.2021; Nature Publishing Group; Nature Portfolio
• Subjects: 140/125; 639/624/400/561; 639/766/119/995; 639/766/1960/1135; 639/766/36/1122; 639/766/930/12; 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ATOMIC AND MOLECULAR PHYSICS; Electrical conductivity; Electrical resistivity; Energy coupling; Evolution; Femtosecond pulses; Free electron lasers; high energy density physics; High temperature; Humanities and Social Sciences; Ion scattering; Laser beam heating; Lasers; Low temperature; MATERIALS SCIENCE; Metal foils; multidisciplinary; Radiation; Science; Science (multidisciplinary); terahertz; Terahertz frequencies; Time; Warm dense matter
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-021-21756-6

Key insights in materials at extreme temperatures and pressures can be gained by accurate measurements that determine the electrical conductivity. Free-electron laser pulses can ionize and excite matter out of equilibrium on femtosecond time scales, modifying the electronic and ionic structures and enhancing electronic scattering properties. The transient evolution of the conductivity manifests the energy coupling from high temperature electrons to low temperature ions. Here we combine accelerator-based, high-brightness multi-cycle terahertz radiation with a single-shot electro-optic sampling technique to probe the evolution of DC electrical conductivity using terahertz transmission measurements on sub-picosecond time scales with a multi-undulator free electron laser. Our results allow the direct determination of the electron-electron and electron-ion scattering frequencies that are the major contributors of the electrical resistivity. The electrical conductivity is critical to understand warm dense matter, but the accurate measurement is extremely challenging. Here the authors use multi-cycle THz pulses to measure the conductivity of gold foils strongly heated by free-electron laser, determining the individual contributions of electron-electron and electron-ion scattering.