Electronic structure of α- and δ-Pu from photoelectron spectroscopy

Abstract

We report photoemission results on \ensuremath{\alpha}- and \ensuremath{\delta}-Pu using a laser plasma light source (LPLS) as well as He light as the exciting radiation. The LPLS is a pseudocontinuum tunable light source with intensities rivaling some second-generation synchrotrons. Both phases of Pu display a narrow, temperature-independent, $5f$-related feature at the Fermi energy, which is narrower in \ensuremath{\delta}-Pu than in \ensuremath{\alpha}-Pu, suggestive of possible heavy-fermion-like behavior. In both \ensuremath{\alpha}-Pu and \ensuremath{\delta}-Pu the photon-energy dependence of this feature suggests some $6d$ admixture, albeit somewhat smaller in \ensuremath{\delta}-Pu. In this respect it differs qualitatively from Ce and U heavy fermions.