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Ultrafast quasiparticle relaxation dynamics in normal metals and heavy fermion materials

K. H. Ahn·M. J. Graf·S. A. Trugman·J. Demsar·R. D. Averitt·J. L. Sarrao·A. J. Taylor
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Abstract

We present a detailed theoretical study of the ultrafast quasiparticle relaxation dynamics observed in normal metals and heavy fermion materials with femtosecond time-resolved optical pump-probe spectroscopy. For normal metals, a nonthermal electron distribution gives rise to a temperature (T) independent electron-phonon relaxation time at low temperatures, in contrast to the T^{-3}-divergent behavior predicted by the two-temperature model. For heavy fermion compounds, we find that the blocking of electron-phonon scattering for heavy electrons within the density-of-states peak near the Fermi energy is crucial to explain the rapid increase of the electron-phonon relaxation time below the Kondo temperature. We propose the hypothesis that the slower Fermi velocity compared to the sound velocity provides a natural blocking mechanism due to energy and momentum conservation laws.

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K. H. Ahn, M. J. Graf, S. A. Trugman, J. Demsar, R. D. Averitt, J. L. Sarrao, A. J. Taylor. 2004-02-18. Ultrafast quasiparticle relaxation dynamics in normal metals and heavy fermion materials. https://doi.org/10.1103/physrevb.69.045114

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