Intermetallic compounds band magnetism

Mossbauer spectroscopy is a powerful tool to gain essential information on the difference in electron structure between intermetallic compounds of 4f and 5f elements. In the latter series the work concentrates on Np materials. For this actinide bulk magnetic and transport data are still scarce and even neutron diffraction results are not plentiful. Mossbauer spectroscopy is thus in some sense a forerunner. It has been shown that measurements under high pressures are pivotal for a deeper insight of electronic properties, in particular with the question of 3d-like itinerant versus 4f-like localized electron behavior of the 5f electrons in Np. It becomes more and more apparent that U and Np behave often quite differently mainly because of the somewhat more pronounced tendency of the latter towards f localization. Nevertheless, the formation of 5f bands via hybridization plays a central role also in Np metallic compounds. 

From an experimental point of view, it appears that the resonant f level is the best starting hypothesis for most U, Np and Pu compounds. Only in some cases of strong hybridization (particularly for Laves phase and AuCua-type structure intermetallics) it will broaden into true bands and we shall try to give criteria for itinerant magnetism. 

These interesting and somewhat unusual properties associated with the B32 type Zintl phases have generated theoretical interest in this area In the present work theoretical investigations of B32 type intermetallic phases will be reported. Furthermore, the optical and magnetic properties found experimentally are interpreted on the basis of the electronic structure of the B32-type compounds gained from band structure calcula-... 

Band structure calculations are needed in order to determine the shape of the Fermi surface in intermetallics. The RKKY model would then have a more respectable foundation if applied to a compound whose Fermi surface is known to be approximately spherical and if the model could be explicitly avoided for the cases where the Fermi surface is distinctly nonspherical. As already mentioned in subsection 2.1 modifications of the RKKY model for general Fermi surface shapes are extremely difficult to apply. Band structure calculations up till now have been confined to the more symmetrical lattices. As a consequence, a very large fraction of such calculations involves the CsCl structure. As a first approximation the objects of the investigations contain no magnetic components, in order to find the undisturbed state of the Fermi surface. When... 

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