Narrow Band Magnetism and Spin-Polarization

We have discussed and distinguished two limiting cases for 5 f wave functions  

Difficulties arise when the d- and f-electrons are in an intermediate state between i. and ii. This is the case for narrow bands (Fig. 12c). This intermediate state of affairs has been at the center of theoretical and experimental investigations for d-transition solids, especially metallic solids  

One important point is whether narrow bands would display permanent magnetic moments and undergo magnetic collective phenomena. This depends clearly upon their bandwidth and will lead again to the problem localization vs itineracy. In band calculations, new ways have to be looked for, since the set of hypotheses examined previously, which hold for non-magnetic solids, must be corrected for spin-polarization. 

These concepts are very importcint also for actinide solids. In particular, the Stoner model for collective magnetism in narrow bands, the frame in which d-transition metals and actinide metals magnetism has been discussed, will be reviewed briefly. 

---