Evidence of a coupled electron-phonon liquid in NbGe2
Hung-Yu Yang, Xiaohan Yao, Vincent Plisson, Shirin Mozaffari, Jan P. Scheifers, Aikaterini Flessa Savvidou, Eun Sang Choi, Gregory T. McCandless, Mathieu F. Padlewski, Carsten Putzke, Philip J. W. Moll, Julia Y. Chan, Luis Balicas, Kenneth S. Burch, Fazel Tafti
Abstract
Abstract 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.