Low temperature magnetic properties of the quasicrystalline Al80Mn12Si4X4 (X = Cr, Y, Sm and Nd) alloys

Quasicrystalline Al80Mn12Si4X4 (X = Cr, Y, Sm and Nd) alloys were produced and their magnetic properties were investigated. X-ray diffraction and scanning electron microscopy revealed the presence of atomic arrangements with pentagonal symmetry. The nature of the coupling of the magnetic moments was investigated for temperatures (T) varying from 2.0 to 300.0 K and for applied magnetic fields in the range +/- 85.0 kOe. The dc magnetic susceptibility indicated that the net magnetic interactions are antiferromagnetic for the samples with Cr and Y. However, the samples with Sm and Nd showed to be ferromagnetic at low-T. The coercivity and the remanence determined from hysteresis loops at 5 K for the sample with Sm (Nd) was, respectively, 0.54 kOe (0.40 kOe) and 0.047 emu/g (0.19 emu/g). A spin-glass-like phase was observed for the AlMnSiNd (AlMnSiSm) sample below 2.7 K (2.4 K). The results are accounted for by taking into consideration the coupling among the rare earth magnetic moments.