From heavy fermions to random-localized-site behaviour via Anderson localization

For sufficiently strong scattering by randomly-distributed imperfections the integrated intensity of a wave initiated at some starting point becomes localized within some finite distance. We discuss how this Anderson localization can be self-induced. with possible enhancement by magnetic ordering, in light actinide systems. This mechanism provides an nb initio based prediction, in close agreement with experiment, of the variation of the magnetic ordering temperatures and low-temperature ordered moments in a number of uranium compounds which are driven by alloying through a phase transition from non-magnetic behaviour to strong magnetic ordering. This mechanism also explains the phase transition to the delta face-centred-cubic (fcc) structure at 592 K in elemental plutonium, which has a low-temperature alpha monoclinic structure, and the substantial depression of melting temperature of plutonium and neptunium with respect to neighbouring elements. Both the strongly magnetically-ordered uranium systems and elemental plutonium in the fee delta phase are described by the if electronic behaviour of a random-localized-fluctuating-site (RLFS) solid-solution-like phase. The physical picture developed here shows that hybridization treated via the Coqblin-Schrieffer resonant-scattering point of view (pertinent in the weak hybridization regime) provides the physical connection (under certain conditions described herein, an actual phase transition) between localized (i.e. coupled magnetic ions) magnetism and strongly-correlated extremely-narrow band behaviour characterized as heavy fermion behaviour in solids. Furthermore, the overall physical picture thus provided for the intermediate delocalized regime of transition-shell electron behaviour (comprising the two subregimes of RLFS random solid-solution-like behaviour and extreme-narrow-band heavy fermion behaviour, respectively) provides the physical connection between localized (e.g. heavy rare earth) and itinerant (e.g. nickel) magnetism.