Binding energies, work-function changes, and saturation moments in the compounds UPt and UPt 2

Abstract

A comparative study of polycrystalline samples of UPt and UPt 2 has been performed with X-ray photoelectron spectroscopy (Al K α radiation) and magnetization measurements. The compound UPt 2 shows ferromagnetic ordering below 10 K with a saturation moment of about 0.1 μ B per atom. The ordering temperature is lower in UPt 2 than in UPt T C = 30 K indicating a decrease of the exchange interaction between the magnetic ions. Valence band and core level spectra as well as work-functions have been measured at room temperature. The 5f electrons seem to be “pinned” at the Fermi energy in pure α-U as well as in the compounds leading to a high density of states at E F. These observations would seem to support an itinerant nature of the 5f electrons in these compounds. Absolute binding energies of the core levels were determined by work-function measurements. The resultant shifts indicate charge transfer from U to Pt consistent with the electronegativity of the elements.