1. Strong electron-phonon coupling and enhanced phonon Gr\'uneisen parameters in valence-fluctuating metal EuPd$_2$Si$_2$
- Author
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Ye, Mai, von Westarp, Mark Joachim Graf, Souliou, Sofia-Michaela, Peters, Marius, Möller, Robert, Kliemt, Kristin, Merz, Michael, Heid, Rolf, Krellner, Cornelius, and Tacon, Matthieu Le
- Subjects
Condensed Matter - Strongly Correlated Electrons - Abstract
We study the valence crossover and strong electron-phonon coupling of EuPd$_2$Si$_2$ by polarization-resolved Raman spectroscopy. The fully-symmetric phonon mode shows strongly asymmetric lineshape at low temperature, indicating Fano-type interaction between this mode and a continuum of electron-hole excitations. Moreover, the frequency and linewidth of the phonon modes exhibit anomalies across the valence-crossover temperature, suggesting the coupling between valence fluctuations and lattice vibration. In particular, two phonon modes show significantly enhanced Gr\"uneisen parameter, suggesting proximity to a critical elasticity regime. The relative contribution of the structural change and valence change to the phonon anomalies is evaluated by density functional theory calculations.
- Published
- 2022
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