Shubnikov-de Haas oscillations and Fermi surfaces in transition-metal pentatellurides ZrTe5and HfTe5

Shubnikov-de Haas (SdH) oscillations are reported for well characterised crystals of the anisotropic conductors ZrTe5, HfTe5 and Hf0.88Zr0.12Te5. In each material, only one cross sectional frequency dominates the oscillations below the temperature of the resistivity anomaly. Shapes of the Fermi surface (FS) are deduced from the dependence of the extremal FS cross sections on the angle between the crystallographic axes of the sample and the magnetic field. The FS obtained is a long cigar-shaped ellipsoid, which indicates the quasi-two-dimensional character of the electronic properties in these pentatellurides. The temperature dependence (0.32