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Displacive Excitation of Coherent Phonons in YBa_2Cu_3 O_7: An Optical Evidence for the Van-Hove Singularity

W. -S. Zeng·J. Kuhl
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Abstract

The amplitude of displacive excitation of coherent phonons ({\it DECP}) in $YBa_2Cu_3O_7$ observed in time-resolved spectroscopy increases by a very large factor of 15 between 20 K (below $T_c$) and 100 K (above $T_c$). Microscopic modelling of phonon excitation reveals that these amplitude changes of the {\it $A_{1g}$} mode phonons are related to the existence of the {\it Van-Hove} singularity (VHS) below but very close to Fermi energy. PACS numbers: 78.47.+p, 74.25.Gz, 74.25.Jb, 71.15.Fv

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W. -S. Zeng, J. Kuhl. 1996-08-26. Displacive Excitation of Coherent Phonons in YBa_2Cu_3 O_7: An Optical Evidence for the Van-Hove Singularity. https://arxiv.org/abs/cond-mat/9601042

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