Studies of the time dependence of the magnetization of T-Al3Mn(Pd,Fe) compounds

The structure of the complex intermetallic compound T-Al3Mn, an approximant of the decagonal quasicrystal, persists by substitution of Pd or Fe for Mn. Magnetically spin glass behaviour is obtained. Relative to the mother compound substitution of Pd (Fe) decreases (increases) the freezing temperature Tf. The time dependence of the magnetic moment points to broad activation energy distributions with similar shape but different centre of gravity. For comparable temperatures the Fe containing compounds exhibit larger height of the barriers than those without and with Pd substitution. For the decagonal quasicrystal the mean effective activation energy is reduced compared to the one for the T-phase compounds.