Electronic Structure and Magnetism of Itinerant 5f Ferromagnets URhSi and URhGe

Abstract

The electronic structure of actinide intermetallic compounds is mainly determined by partially occupied f-electron states. The magnetic and other electronic properties have, however, only little in common with the behavior of their lanthanide counterparts, and in many cases they resemble3d,4d,or5d transition metal intermetallics. This is particularly visible when comparing physical properties of light lanthanide with light actinide intermetallics. In the former case the 4f-states are usually atomic-like, in contrast to the delocalized Bloch-like 5f-states in the latter case. The nature of the 5f-states can be also remarkably affected by external variables like pressure and magnetic field as well as by alloying with other elements. Thus a wide range of properties of light actinide compounds is connected with the degree of localization of the 5f-electrons including the strongly correlation regime, which gives rise to exotic phenomena like heavy fermion behavior and superconductivity. Another important ingredients of 5f-magnetism are the relativistic effects especially the spin-orbit (SO) interaction, which provides significant orbital polarization of the5f band and leads to a huge magnetocrystalline anisotropy frequently observed e.g. in uranium intermetallics.