Electron-phonon coupling and superconductivity-induced distortion of the phonon lineshape in V${}_3$Si

Abstract

Phonon measurements in the A15-type superconductors were complicated in the past because of the unavailability of large single crystals for inelastic neutron scattering, e.g., in the case of Nb${}_3$Sn, or unfavorable neutron scattering properties in the case of V${}_3$Si. Hence, only few studies of the lattice dynamical properties with momentum resolved methods were published, in particular below the superconducting transition temperature $T_c$. Here, we overcome these problems by employing inelastic x-ray scattering and report a combined experimental and theoretical investigation of lattice dynamics in V${}_3$Si with the focus on the temperature-dependent properties of low-energy acoustic phonon modes in several high-symmetry directions. We paid particular attention to the evolution of the soft phonon mode of the structural phase transition observed in our sample at $T_s=18.9\mathrm{K}$, i.e., just above the measured superconducting phase transition at $T_c=16.8\mathrm{K}$. Theoretically, we predict lattice dynamics including electron-phonon coupling based on density-functional-perturbation theory and discuss the relevance of the soft phonon mode with regard to the value of $T_c$. Furthermore, we explain superconductivityinduced anomalies in the lineshape of several acoustic phonon modes using a model proposed by Allen et al., [Phys. Rev. B 56, 5552 (1997)].

References in corpus (8)

• Superconductivity in the A15 Structure
• Observation of a Charge Density Wave Incommensuration Near the Superconducting Dome in CuxTiSe2
• Pressure dependence of the charge-density-wave and superconducting states in GdTe${}_3$, TbTe${}_3$ and DyTe${}_3$
• Energy Gaps and Kohn Anomalies in Elemental Superconductors
• Momentum-resolved electron-phonon interaction in lead determined by neutron resonance spin-echo spectroscopy
• Superconductivity and hybrid soft modes in TiSe${}_2$
• Superconductivity-Induced Distortions of Phonon Lineshapes in Niobium
• Superconducting energy gap of $2H$-NbSe${}_2$ in phonon spectroscopy