engleski

Anisotropic magnetic, electrical and thermal transport properties of Y-Al-Ni-Co decagonal approximant

We have investigated anisotropic physical properties (magnetic susceptibility, electrical resistivity, thermoelectric power, Hall coefficient and thermal conductivity) of Y-Al- Ni-Co decagonal approximant with composition Al76Co22Ni2. The crystalline-direction- dependent measurements were performed along three orthogonal directions a*, b and c of the Y-Al-Ni-Co unit cell, where (a, c) monoclinic atomic planes are stacked along the perpendicular b direction. Anisotropic magnetic susceptibility of conduction electrons is paramagnetic for the field lying within the (a, c) atomic planes and diamagnetic for the field along the b direction. Anisotropic electrical resistivity is low in all crystalline directions, appearing in the order . Thermopower shows electron-phonon enhancement effect. Anisotropic bare thermopower (in the absence of electron-phonon interactions) was extracted, appearing in the same order as the resistivity, . Anisotropic thermal conductivity appears in the order , so that b is the most conducting direction for both electricity and heat. Hall coefficient exhibits pronounced anisotropy, where the magnetic field in a given direction yields the same irrespectively of the direction of the current in the perpendicular plane. These anisotropies are analyzed in terms of the anisotropic structure of the Y-Al-Ni-Co phase and the ab initio calculated anisotropic Fermi surface. The results are compared to the literature-reported anisotropy of the physical properties of the d-Al-Ni-Co decagonal quasicrystal.

Quasicrystals

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