Anisotropic physical properties of theAl13Fe4complex intermetallic and its ternary derivativeAl13(Fe,Ni)4

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We have investigated the magnetic susceptibility, the electrical resistivity, the specific heat, the thermoelectric power, the Hall coefficient, and the thermal conductivity of the ${\text{Al}}_{13}{\text{Fe}}_{4}$ and ${\text{Al}}_{13}{(\text{Fe},\text{Ni})}_{4}$ monoclinic approximants to the decagonal quasicrystal. While the ${\text{Al}}_{13}{\text{Fe}}_{4}$ crystals are structurally well ordered, the ternary derivative ${\text{Al}}_{13}{(\text{Fe},\text{Ni})}_{4}$ contains substitutional disorder and is considered as a disordered version of the ${\text{Al}}_{13}{\text{Fe}}_{4}$. The crystallographic-direction-dependent measurements were performed along the ${a}^{\ensuremath{\ast}}$, $b$, and $c$ directions of the monoclinic unit cell, where the $({a}^{\ensuremath{\ast}},c)$ atomic planes are stacked along the $b$ direction. The electronic transport and the magnetic properties exhibit significant anisotropy. The stacking $b$ direction is the most conducting direction for the electricity and heat. The effect of substitutional disorder in ${\text{Al}}_{13}{(\text{Fe},\text{Ni})}_{4}$ is manifested in the large residual resistivity $\ensuremath{\rho}(T\ensuremath{\rightarrow}0)$ and significantly reduced thermal conductivity of this compound, as compared to the ordered ${\text{Al}}_{13}{\text{Fe}}_{4}$. Specific-heat measurements reveal that the electronic density of states at the Fermi level of both compounds is high. The anisotropic Hall coefficient ${R}_{H}$ reflects complex structure of the anisotropic Fermi surface that contains electronlike and holelike contributions. Depending on the combination of directions of the current and the magnetic field, electronlike $({R}_{H}l0)$ or holelike $({R}_{H}g0)$ contributions may dominate, or the two contributions compensate each other $({R}_{H}\ensuremath{\approx}0)$. Similar complicated anisotropic behavior was observed also in the thermopower. The anisotropic Fermi surface was calculated ab initio using the atomic parameters of the refined ${\text{Al}}_{13}{\text{Fe}}_{4}$ structural model that is also presented in this work.