Fermi surface topology and electronic transport properties of a chiral crystal NbGe${}_2$ with strong electron-phonon interaction

Abstract

We report the electronic structures and transport properties of a chiral crystal NbGe${}_2$, which is a candidate for a coupled electron-phonon liquid. The electrical resistivity and thermoelectric power of NbGe${}_2$ exhibit clear differences compared to those of NbSi2 even though both niobium ditetrelides are isostructural and isoelectronic. We discuss the intriguing transport properties of NbGe${}_2$ based on a van Hove-type singularity in the density of states. The analysis of de Haas-van Alphen oscillations measured by the field modulation and magnetic torque methods reveals the detailed shape of the Fermi surface of NbGe${}_2$ by comparison with the results of energy band structure calculations using a local density approximation. The electron and hole Fermi surfaces of NbGe${}_2$ split into two because of the anti-symmetric spin-orbit interaction. The temperature dependence of quantum oscillations indicates that the effective mass is isotropically enhanced in NbGe${}_2$ due to strong electron-phonon interaction.

9 pages, 7 figures, To be published in Phys. Rev. B