Unusual spin-glass phase in icosahedral Tb-Mg-Zn quasicrystals

The nature of the spin state below the spin freezing temperature was studied in an icosahedral Th-Mg-Zn quasicrystal by thermoremanent dc magnetization time decay as a function of aging time and magnetic field. The system does not exhibit a highly degenerate free-energy landscape obeying an ultrametric organization of metastable states, which makes it essentially different from canonical spin glasses. The Th-Mg-Zn system can be considered as a special class of spin glass, which possesses some local order, but still preserves the notion of spin freezing.