Tracking the ultrafast nonequilibrium energy flow between electronic and lattice degrees of freedom in crystalline nickel

Femtosecond laser excitation of solid-state systems creates out-of-equilibrium hot electrons that cool down by transferring their energy to other degrees of freedom and ultimately to lattice vibrations of the solid. By combining ab initio calculations with ultrafast diffuse electron scattering, we gain a detailed understanding of the complex nonequilibrium energy transfer between electrons and phonons in laser-excited Ni metal. Our experimental results show that the wave-vector-resolved population dynamics of phonon modes is distinctly different throughout the Brillouin zone and are in remarkable agreement with our theoretical results. We find that zone-boundary phonon modes become occupied first. As soon as the energy in these modes becomes larger than the average electron energy, a backflow of energy from lattice to electronic degrees of freedom occurs. Subsequent excitation of lower-energy phonon modes drives the thermalization of the whole system on the picosecond time scale. We determine the evolving nonequilibrium phonon occupations, which we find to deviate markedly from thermal occupations.

Chase, T.SLAC Natl Accelerator Lab, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA;Stanford Univ, Dept Appl Phys, Stanford, CA 94305 USA (författare)
Reid, A. H.SLAC Natl Accelerator Lab, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA (författare)
Shen, X.SLAC Natl Accelerator Lab, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA (författare)
Li, R. K.SLAC Natl Accelerator Lab, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA (författare)
Carva, K.Charles Univ Prague, Fac Math & Phys, Dept Condensed Matter Phys, Ke Karlovu 5, CZ-12116 Prague 2, Czech Republic (författare)
Payer, T.Univ Duisburg Essen, Dept Phys, D-47057 Duisburg, Germany;Univ Duisburg Essen, Ctr Nanointegrat Duisburg Essen CENIDE, D-47057 Duisburg, Germany (författare)
von Hoegen, M. HornUniv Duisburg Essen, Dept Phys, D-47057 Duisburg, Germany;Univ Duisburg Essen, Ctr Nanointegrat Duisburg Essen CENIDE, D-47057 Duisburg, Germany (författare)
Sokolowski-Tinten, K.Univ Duisburg Essen, Dept Phys, D-47057 Duisburg, Germany;Univ Duisburg Essen, Ctr Nanointegrat Duisburg Essen CENIDE, D-47057 Duisburg, Germany (författare)
Wang, X. J.SLAC Natl Accelerator Lab, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA (författare)
Oppeneer, Peter M.Uppsala universitet,Materialteori(Swepub:uu)peopp623 (författare)
Dürr, HermannUppsala universitet,FREIA,SLAC Natl Accelerator Lab, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA(Swepub:uu)herdu191 (författare)
Uppsala universitetMaterialteori (creator_code:org_t)

Av författaren/redakt...: Maldonado, Pablo; Chase, T.; Reid, A. H.; Shen, X.; Li, R. K.; Carva, K.; visa fler...; Payer, T.; von Hoegen, M. H ...; Sokolowski-Tinte ...; Wang, X. J.; Oppeneer, Peter ...; Dürr, Hermann; visa färre...

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