engleski

Hall effect of the approximants to decagonal quasicrystals

The Hall effect has been studied in single crystals of monoclinic Y-Al-Ni-Co[1, 2], orthorhombic o-Al13Co4[3], monoclinic m-Al13Fe4 and m-Al13(Fe, Ni)4[4] and Taylor phase T- Al73(Mn, Fe)27[5]. The Hall coefficient RH of each alloy has been measured for all combinations of the electrical current and magnetic field directions and in the temperature interval from 90 to 370 K. In the first four samples, which belong to the Al13TM4 (TM = transition metal) class of approximants to the decagonal quasicrystals (d- QCs), the Hall coefficient exhibits well defined anisotropy: RH is positive hole-like or zero for the magnetic field parallel to the plane that corresponds to the quasiperiodic plane in d-QCs, and is negative electron-like or zero for the magnetic field perpendicular to this plane. The only exception is RH in Al13Fe4 for the field parallel to the stacking direction, which changes the sign from positive to negative value with the increase of temperature. The results for the anisotropy of RH are correlated to the anisotropy of RH in d-Al-Ni-Co and d-Al-Cu-Co [6] quasicrystals and a brief overview of the theoretical results is presented [7]. In T- Al73(Mn, Fe)27 the Hall effect contains both normal and anomalous (magnetic) Hall effect. Therefore, the results for the magnetic susceptibility were used for the separation of these two contributions. It was found that neither the normal nor the anomalous Hall coefficient depend significantly on the direction of the magnetic field and current with the respect to the crystalline axes.

Hall effect ; anisotropy ; approximants

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