As can be seen in Figure 6.3 the HoFe film has a markedly different Mössbauer spectrum compared to YFe and DyFe. Unfortunately this may not be a pure HoFe spectrum as, due to the thinness of the sample layer, part of the spectrum will be recorded from the YFe seed layer.
Using the CEMS theory outlined in Section 2.5.2 an upper limit can be placed on the relative spectral contributions from the two layers. For a sample layer the ratio of sample to seed layer is :. Thus the spectrum is more akin to that from a HoFe/YFe bilayer. Hence we cannot analyse the spectrum to give any accurate information about a HoFe thin film due to the overlap of the two sub-spectra and any possible interface effects.
In the DyFe thin film this ratio is : giving a more representative spectrum of the sample layer. In the YFe thin film this effect does not apply as the sample and seed layer are the same material and continuous.
Dr John Bland, 15/03/2003