DUAL CHARACTER OF 5F ELECTRONS IN UPD2AL3 OBSERVED BY HIGH-RESOLUTIONPHOTOEMISSION SPECTROSCOPY

Comparative high-resolution temperature-dependent photoemission measur ements were performed for UPd2Al3 and UPd3. The photoemission spectrum near E(F) of UPd2Al3 consists of a sharp peak at E(F) and a broad ban d at 0.5-1.0 eV binding energy, both features having U 5f character. T he sharp feature at E(F) shows good agreement with a recent band struc ture calculation, while the broad band matches well with the U 5f-deri ved localized feature in UPd3, indicating the dual character of 5f ele ctrons in UPd2Al3. The intensity of the broad band relative to the E(F )-peak increases with increasing temperature, suggesting that the loca lized character of 5f electrons in UPd2Al3 increases at higher tempera tures. These observations are consistent with the transport and magnet ic measurements which imply a temperature-dependent dual (itinerant an d localized) character of U 5f electrons in UPd2Al3.