Weak-itinerant ferromagnetism

By using this low temperature superimposed susceptibility, the transition temperature and the Curie constant immediately above Tc, Dunlap et al. found that NpOs2 fulfilled the Murata-Doniach requirements for a weak itinerant ferromagnet ... 

There are a few exceptions, such as very weak itinerant ferromagnets (for example ZrZn2) and low-spin high-spin transition in fee iron. 

Very weak itinerant ferromagnets, defined as materials for which the splitting in energy between the + and - bands is very small, are predicted to have a number of distinctive properties. In particular, the value of the ratio qc/q% should be much greater than unity and roughly inversely proportional to the Curie temperature (Rhodes and Wohlfarth 1963). Here qc is obtained from the observed paramagnetic susceptibility using the relationship... 

The current view of these and of the off-stoichiometric (Fe0 5 Co0 5), >,Ti y alloys seems to be that they can be correctly represented by an itinerant part which is well-described in terms of the SEW model of weak-itinerant ferromagnetism but that there is additional moment formation associated with Fe or Co atoms on Ti sites (antistructure atoms) in the region of 0 < x < 0.35 leading to localized effects (Buis et al. 1981b). Parviainen (1982) has shown that the observation of a negative... 

UNi2 behaves as a weak itinerant ferromagnet. The value Tc — 20-21 K was determined on polycrystals (Sechovsky et al. 1980a, Havela et al. 1980) while Tc = 27 K (Frings et al. 1986) was found on a single crystal. The most appropriate value, however, would be Tc = 24 K which corresponds to a peak in the C(T) data (Frings et al. 1986). A very low spontaneous moment jus = 0.08jaB/f.u. locked in the... 

For the LU3C07 778714 compound measurements of flie bulk magnetization and susceptibility were carried out over the temperature range 4-300 K (Skolozdra et al. 1996a). It turns out that it is a very weak itinerant ferromagnet with Tc=63 K and the Co moment of 0.19jttB at 4 K. Above 63 K x(T) follows the Curie-Weiss law (fig. 26), and the elfective... 

NMR nuclear magnetic resonance VWIF very weak itinerant ferromagnetism... 

Three types of characteristic behaviours are mainly observed for R concentrations near or larger than the critical ones, namely collective electron metamagnetism (CEM), very weak itinerant ferromagnetism (VWIF) and Co antiferromagnetism. 

Correspondingly, there exist (i) paramagnetic, (ii) weakly itinerant ferromagnetic, and (iii) strongly itinerant ferromagnetic materials. 

---