Mössbauer spectroscopy investigation of body centered cubic Co in Co/Fe superlattices prepared with MBE

Local magnetic effects of interface alloying in Fe/Co superlattices

“…Our results also show that the calculated hyperfine fields do not reproduce the experimental values. Compared with experimental data, our method underestimates the B hf for bulk bcc Fe by ∼3 T and the B hf for Fe in bcc Co [12] is overestimated by ∼4 T. This can be explained by the limitations of the approximations made within the LSDA and the ASA, but also by the fact that we only calculate the Fermi contact contribution to the hyperfine field. The oscillating behaviour seen for the perfect interfaces in both 5/7 and 9/7, as well as for the 9/7 multilayer with interface alloying, can be explained by the non-linear behaviour of the B hf for Fe in bulk Fe-Co alloys, as shown earlier in figure 7.…”

“…In the past, a large number of local-probe studies have been devoted to bulk Fe-Co alloys and their magnetic properties [3][4][5][6][7][8][9][10]. As a natural continuation of this, in more recent years, the development in epitaxial deposition techniques has led to theoretical and experimental investigations of Fe/Co multilayers [11][12][13][14][15][16][17][18][19], with properties that in many respects are different from those of bulk samples. There are, however, quite a few discrepancies between the results from different experimental techniques in the previous studies.…”

High-energy phonon confinement in nanoscale metallic multilayers

“…This broadening clearly indicates the presence of a distribution of 57 Fe sites in these multilayers. These 57 Fe sites may be attributed to a combination of several configurations: 22,23 ␣-Fe ͑B hf = 33.0 T͒, bcc-Co ͑31.2 T͒, Fe/Co interface region ͑35.4 T, enhanced͒, and hcp-Co ͑ϳ32 T͒. Since the P͑B hf ͒ range in Fig.…”

Multipurpose setup for low-temperature conversion electron Mössbauer spectroscopy

“…Such cases require the detection of conversion electrons emitted from the surface or near-surface region (escape depth of ∼200 nm in the case of 57 Fe 4 ). Successful thin film studies at room temperature already showed a relevant contribution of conversion electron Mössbauer spectroscopy (CEMS) measurement on, e.g., the investigation of the tetragonal distortion of ultrathin (down to 14 Å) silicide layers in Fe/CsCl-57 FeSi/Fe sandwiches 5 or of thin body centered cubic Co layers prepared in Fe/Co superlattices doped with 57 Co. 6 Measurements at lower temperature would be beneficial to disentangle different components in complex spectra, e.g., in thin Fe 1x Si layers on Si, 7 provided the temperature dependence of the hyperfine parameters can a) Electronic mail: valerie.augustyns@kuleuven.be b) Electronic mail: lino.pereira@kuleuven.be be determined. Whereas cryostats are widely used for transmission Mössbauer spectroscopy, performing conversion electron Mössbauer spectroscopy (CEMS) measurements at low temperatures is far less straightforward.…”