Dual Character of 5f Electrons in UPd2Al3Observed by High-Resolution Photoemission Spectroscopy

Comparative high-resolution temperature-dependent photoemission measurements were performed for UPd 2 Al 3 and UPd 3 . The photoemission spectrum near E F of UPd 2 Al 3 consists of a sharp peak at E F and a broad band at 0.5–1.0 eV binding energy, both features having U 5f character. The sharp feature at E F shows good agreement with a recent band structure calculation, while the broad band matches well with the U 5f-derived localized feature in UPd 3 , indicating the dual character of 5f electrons in UPd 2 Al 3 . The intensity of the broad band relative to the E F -peak increases with increasing temperature, suggesting that the localized character of 5f electrons in UPd 2 Al 3 increases at higher temperatures. These observations are consistent with the transport and magnetic measurements which imply a temperature-dependent dual (itinerant and localized) character of U 5f electrons in UPd 2 Al 3 .