Magnetic and conversion electron mossbauer-spectroscopy studies in FE/TA multilayers

We have prepared Fe/Ta multilayers by rf sputtering. A small 1-cm2 chip of Fe-57 was placed on the Fe target. We studied the magnetization (M) and M-H loops and also carried out conversion electron Mossbauer spectroscopy (CEMS). The in-plane loops are rectangular with a lowest coercivity of 2.6 Oe. Magnetization studies indicate a dead Fe layer about 5 angstrom thick at each interface. CEMS spectra for samples with t(Fe) greater-than-or-equal-to 54 angstrom showed a typical six-line pattern, indicating the presence of bulk Fe. No other Fe sites could be detected. However, for t(Fe) = 24 angstrom, where almost 50% of Fe is nonmagnetic, CEMS spectra showed the presence of a strong paramagnetic doublet