We report the electronic structures and transport properties of a chiral
crystal NbGe2β, which is a candidate for a coupled electron-phonon liquid.
The electrical resistivity and thermoelectric power of NbGe2β exhibit clear
differences compared to those of NbSi2 even though both niobium ditetrelides
are isostructural and isoelectronic. We discuss the intriguing transport
properties of NbGe2β 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 NbGe2β by comparison with the results of energy band structure
calculations using a local density approximation. The electron and hole Fermi
surfaces of NbGe2β 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 NbGe2β due to strong
electron-phonon interaction.Comment: 9 pages, 7 figures, To be published in Phys. Rev.