Magnetic and hyperfine interaction in RFe4Al8 (R = Ce, Sc) compounds

Magnetic properties of ScFe4Al8 and CeFe4Al8 compounds have been studied by magnetization and Mossbauer effect measurements. Magnetic transition tempe ratures estimated from Mossbauer spectra (B = 0) 170 K for CeFe4Al8 and 225 K for ScFe4Al8 are not confirmed by magnetization measurements. Contrary, the pronounced maxima at T-max = 130 and 125 K in DC magnetization curves ( B = 1 kOe) were found for ScFe4Al8 and CeFe4Al8, respectively, Thermomagnet ic, the so-called zero field (ZFC) and field cooling (FC) experiments show temperature-dependent irreversibilities below the "freezing" temperature, T -f, which diminishes with application of external magnetic field. The Mossb auer studies show the coexistence of magnetically (sextet) and non-magnetic ally (quadrupole doublet) split patterns in the wide temperature range far away from T-max. All these observations indicate that the systems studied a re either a spin-glass or are the mixture of AF and spin-glass state. (C) 2 001 Elsevier Science B.V. All rights reserved.