Smontara, Ana; Smiljanic, Igor; Ivkov, Jovica; Stanic, Denis; Barišić, Osor S.; Jagličić, Z.; Gille, Peter; Komelj, M.; Jeglič, P.; Bobnar, M.; Dolinšek, Janez
Anisotropic magnetic, electrical, and thermal transport properties of the Y-Al-Ni-Co decagonal approximant.
In: Physical Review B - Condensed Matter and Materials Physics, Vol. 78, No. 10
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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 Al76 Co22 Ni2. 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 ρ a > ρc ρb. 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, | S a bare/T | > | Sc bare/T | > | Sb bare/T |. Anisotropic thermal conductivity appears in the order κb > κc > κ a, so that b is the most conducting direction for both electricity and heat. Hall coefficient RH exhibits pronounced anisotropy, where the magnetic field in a given crystalline direction yields the same RH for the current along the other two crystalline directions 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 with the literature-reported anisotropy of the physical properties of the d -Al-Ni-Co decagonal quasicrystal.