Evidence of a coupled electron-phonon liquid in NbGe2

• Published in: Nature communications 2021-09, Vol.12 (1), p.5292-5292, Article 5292
• Main Authors: Yang, Hung-Yu, Yao, Xiaohan, Plisson, Vincent, Mozaffari, Shirin, Scheifers, Jan P., Savvidou, Aikaterini Flessa, Choi, Eun Sang, McCandless, Gregory T., Padlewski, Mathieu F., Putzke, Carsten, Moll, Philip J. W., Chan, Julia Y., Balicas, Luis, Burch, Kenneth S., Tafti, Fazel
• Format: Article
• Language: English
• Subjects: 639/766/119/995; Computational fluid dynamics; CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; Electron phonon interactions; Electronic properties and materials; Electrons; Elementary excitations; Fermi liquids; Fluid flow; Heavy metals; Humanities and Social Sciences; Hydrodynamics; Laboratories; Metals; Momentum; multidisciplinary; Oscillations; Phonons; Raman spectra; Science; Science (multidisciplinary); Symmetry; Transition metals
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-021-25547-x

Whereas electron-phonon scattering relaxes the electron’s momentum in metals, a perpetual exchange of momentum between phonons and electrons may conserve total momentum and lead to a coupled electron-phonon liquid. Such a phase of matter could be a platform for observing electron hydrodynamics. Here we present evidence of an electron-phonon liquid in the transition metal ditetrelide, NbGe 2 , from three different experiments. First, quantum oscillations reveal an enhanced quasiparticle mass, which is unexpected in NbGe 2 with weak electron-electron correlations, hence pointing at electron-phonon interactions. Second, resistivity measurements exhibit a discrepancy between the experimental data and standard Fermi liquid calculations. Third, Raman scattering shows anomalous temperature dependences of the phonon linewidths that fit an empirical model based on phonon-electron coupling. We discuss structural factors, such as chiral symmetry, short metallic bonds, and a low-symmetry coordination environment as potential design principles for materials with coupled electron-phonon liquid. It was predicted that in the regime of strong electron-phonon interactions, electrons and phonons can form a coupled non-equilibrium state, characterized by the conservation of the total momentum and by hydrodynamic transport. Here, the authors report experimental evidence for such a coupled electron-phonon liquid in NbGe 2 .