Strong electron-phonon coupling and enhanced phonon Grüneisen parameters in valence-fluctuating metal EuPd${}_2$Si${}_2$

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 Grüneisen 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.

References in corpus (10)

• Inelastic Light Scattering From Correlated Electrons
• Raman scattering study of vibrational and magnetic excitations in Sr${}_{2-x}$La${}_x$IrO${}_4$
• Lattice dynamics of the excitonic insulator Ta${}_2$Ni(Se${}_{1-x}$S${}_x$)${}_5$
• An Electronic Nematic Liquid in BaNi${}_2$As${}_2$
• Strange semimetal dynamics in SrIrO${}_3$
• Raman spectroscopy of $f$-electron metals: an example of CeB${}_6$
• Influence of the Pd-Si ratio on the valence transition in EuPd${}_2$Si${}_2$ single crystals
• Lattice dynamics, crystal-field excitations and quadrupolar fluctuations of YbRu${}_2$Ge${}_2$
• Crystal-field excitations and vibronic modes in triangular-lattice spin-liquid candidate TbInO${}_3$
• Microscopic analysis of the valence transition in tetragonal EuPd${}_2$Si${}_2$

Cited by in corpus (2)

• Pressure study on the interplay between magnetic order and valence-change crossover in EuPd${}_2$(Si${}_{1-x}$Ge${}_x$)${}_2$
• From valence fluctuations to long-range magnetic order in EuPd${}_2$(Si${}_{1-x}$Ge${}_x$)${}_2$ single crystals