Evidence of a coupled electron-phonon liquid in NbGe$_2$
Hung-Yu Yang, Xiaohan Yao, Vincent Plisson, Shirin Mozaffari, Jan P. Scheifers, Aikaterini Flessa Savvidou, Gregory T. McCandless, Mathieu F. Padlewski, Carsten… 展开作者
Hung-Yu Yang, Xiaohan Yao, Vincent Plisson, Shirin Mozaffari, Jan P. Scheifers, Aikaterini Flessa Savvidou, Gregory T. McCandless, Mathieu F. Padlewski, Carsten Putzke, Philip J. W. Moll, Julia Y. Chan, Luis Balicas, Kenneth S. Burch, Fazel Tafti
Whereas electron-phonon scattering typically relaxes the electron's momentum in metals, a perpetual exchange of momentum between phonons and electrons conserves total momentum and can lead to a coupled electron-phonon liquid with unique transport properties. This theoretical idea was proposed decades ago and has been revisited recently, but the experimental signatures of an electron-phonon liquid have been rarely reported. We present evidence of such a behavior in a transition metal ditetrelide, NbGe$_2$, from three different experiments. First, quantum oscillations reveal an enhanced quasiparticle mass, which is unexpected in NbGe$_2$ due to weak electron-electron correlations, hence pointing at electron-phonon interactions. Second, resistivity measurements exhibit a discrepancy between the experimental data and calculated curves within a standard Fermi liquid theory. Third, Raman scattering shows anomalous temperature dependence of the phonon linewidths which fits 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 sources of coupled electron-phonon liquids.
Insulator to Metal Transition, Spin-Phonon Coupling, and Potential Magnetic Transition Observed in Quantum Spin Liquid Candidate LiYbSe$_2$ under High Pressure
