ON MAGNETIC INTERACTIONS IN QUASICRYSTALLINE Al//8//6Mn//1//4 AND Al//7//5Mn//2//0Si//5 ALLOYS

Low temperature specific heat and ac susceptibility studies on quasicrystalline Al//8//6Mn//1//4 and Al//7//5Mn//2//0Si//5 show that most Mn's are nonmagnetic. The fraction of magnetic Mn's (about 5-10% of all Mn atoms) exhibit spin-glass behavior which in the case of AlMnSi is comparable to that of canonical spin-glasses like Ag-Mn or Cu-Mn. Nuclear hyperfine specific heat term, spin-glass ordering temperature and magnetoresistance, all indicate an enhanced magnetic character in quasicrystalline AlMnSi as compared to AlMn//1//4.