Hall effect in the Y-Al-Ni-Co and o-Al13Co4 decagonal approximants

The Hall effect in Y-Al-Ni-Co and o-Al13Co4 single crystals has been investigated for all combinations of the electrical current and magnetic field directions and in the temperature interval from 90 to 380 K. In these intermetallics the Hall coefficient RH exhibits well defined anisotropy and only weak temperature dependence. RH is negative electron-like or zero for the magnetic field perpendicular to the plane that corresponds to the quasiperiodic plane in decagonal quasicrystals, and is positive hole-like or zero for the magnetic field parallel to this plane. The results for the anisotropy of RH are well correlated to the anisotropy of RH in d-Al-Ni-Co and d-Al-Cu-Co quasicrystals. Therefore, the anisotropy in both crystalline and quasicrystaline samples originates from the specific stacked-layer structure and the chemical decoration of the lattice. The investigated anisotropic RH in Y-Al-Ni-Co was reproduced theoretically by calculation using Boltzmann transport theory, ab-initio calculated anisotropic Fermi surface, and isotropic relaxation time approximation.