Berlin 2005 – scientific programme
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M: Metallphysik
M 28: Elektronische Eigenschaften
M 28.2: Talk
Monday, March 7, 2005, 10:45–11:00, TU H2038
Correlation-induced double-plasmon excitation in Al and Na — •C. Sternemann1, S. Huotari2, M. Volmer1, G. Vanko2, G. Monaco2, M. Tolan1, and W. Schülke1 — 1Institute of Physics, University of Dortmund, D-44221 Dortmund, Germany — 2ESRF, BP 220, F-38043 Grenoble Cedex 9, France
Although the dynamic structure factor S(q, ω) of simple metals has been discussed extensively in terms of electron-ion interaction and electron-electron correlation, the separation of these two contributions in the analysis of S(q, ω) is not straightforward. In this study, a new type of structure in the S(q, ω) of simple metals was found. This structure originates solely from dynamic correlation effects in the homogeneous electron gas, and is not largely affected by electron-ion interaction.
The non-resonant inelastic x-ray scattering experiments have been performed at beamline ID16 of ESRF. The photon energy-loss spectra of both Al and Na have been measured for momentum-transfers between 0.7 qc and 1.5 qc, i.e. across the plasmon cut-off vector qc . For the first time, peaklike structures were found in the high-energy-loss tail of the dynamic structure factor of both metals. According to their shape, the q-dependence of their peak energies and intensities, these structures can be attributed to intrinsic plasmon-plasmon excitations, as proposed theoretically by Sturm and Gusarov [1]. Thus a new type of feature in S(q,w) has been observed which may give the opportunity to probe effects that are of second order in the dynamically screened Coulomb interaction.
[1] K. Sturm and A. Gusarov, Physical Review B 62, 16474 (2000)