Mossbauer effect hyperfine field

The antiferrimagnetic coupling between Tb and Fe moments has been studied by Mossbauer spectra measured in an external field (Scholz et al. 1991). As can be seen from fig. 32, we obtain an increase of the effective hyperfine field with external field independent of its orientation (5p(4.2K, 5T) = 3.27T, where Bp is the peak value of the hyperfine field) this means that Tb aligns preferentially along the external field direction, and that Fe and Tb moments are on the average antiparallel, similar to Fe-Tb alloys. 

Alloys of Pd-Au-Fe (2 at%) Mossbauer effect in Fe and Au, study of band filling, hyperfine fields, isomer shifts... 

The superparamagnetic properties of -Fe203 have also been studied via the Mossbauer effect. Nakamura et al, (32) have investigated the temperature dependence of the internal field in -Fe203 particles of approximately 50 A. diameter. At 120 °K. they obtain a spectrum which is almost identical to the bulk material, except that no Morin transition has occurred and the spins still lie in the basal plane. At room temperature the magnetic hyperfine spectrum collapses (even though the bulk... 

The magnetic hyperfine splitting (MHS) depends on the nuclear spin quantum numbers and /g of the excited and ground state of the Mossbauer nucleus and on the effective magnetic field at the Mossbauer nucleus, which includes contributions from the local electronic spin, from the orbital momentum, from dipole terms, and from external fields. 

The 166Er Mossbauer effect in Er2Fe14B was studied by Sanchez et al. (1986) who found that the spectrum observed at 4.2 K cannot be resolved into two different subspectra. From this these authors conclude that the electronic ground state of the Er atoms at the two crystallographic sites (4f and 4g) are nearly identical. The electronic ground state was further specified by the authors on the basis of the 166 Er hyperfine field observed, and by application of eq. (15), using values for the... 

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