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Dynamics of Excited Electrons in Copper and Ferromagnetic Transition Metals: Theory and Experiment

R. Knorren·K. H. Bennemann·R. Burgermeister·M. Aeschlimann
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Abstract

Both theoretical and experimental results for the dynamics of photoexcited electrons at surfaces of Cu and the ferromagnetic transition metals Fe, Co, and Ni are presented. A model for the dynamics of excited electrons is developed, which is based on the Boltzmann equation and includes effects of photoexcitation, electron-electron scattering, secondary electrons (cascade and Auger electrons), and transport of excited carriers out of the detection region. From this we determine the time-resolved two-photon photoemission (TR-2PPE). Thus a direct comparison of calculated relaxation times with experimental results by means of TR-2PPE becomes possible. The comparison indicates that the magnitudes of the spin-averaged relaxation time τand of the ratio τ_\uparrow/τ_\downarrow of majority and minority relaxation times for the different ferromagnetic transition metals result not only from density-of-states effects, but also from different Coulomb matrix elements M. Taking M_Fe > M_Cu > M_Ni = M_Co we get reasonable agreement with experiments.

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R. Knorren, K. H. Bennemann, R. Burgermeister, M. Aeschlimann. 2000-02-19. Dynamics of Excited Electrons in Copper and Ferromagnetic Transition Metals: Theory and Experiment. https://doi.org/10.1103/physrevb.61.9427

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