Resonant photoemission study of U(x)La(1-x)Pd2Al3

Abstract

In order to further examine the nature of U 5f electrons in UPd2Al3, resonant photoemission studies were performed on alloys U(x)La(1-x)Pd2Al3, in which the contribution from U 5f band states was reduced by substitution of U-atoms with La-atoms. The experiments were performed at the Beamline (BL)-2 of the Synchrotron Orbital Radiation Ring (SOR-Ring). No oxygen signal were detected during the course of measurements. U 5f spectra were obtained by subtracting off-resonance spectra from on-resonance spectra. The 5f spectra displayed a generic triangular shape having a very large amplitude near the Fermi level (E(sub F)) and tailing off slowly to high binding energies, and did not correspond to the calculated results even for x = 1. The essential feature of the experimental spectra did not change even for x = 0.1. This implies that these spectra reflect mostly the single site effects even though the ground state properties of the sample are well described within the band theory.

UPd2Al3中のU-5f電子の特質をさらによく調べるため、U原子をLa原子で置換して、U-5fバンド状態からの寄与を減少した合金、U(x)La(1-x)Pd2Al3の共鳴光電子放出を調べた。実験はシンクロトロン放射リング(SOR-Ring)のビームライン(BL)-2で行った。測定中、酸素の信号は現れなかった。U-5fのスペクトルはオンレゾナンス・スペクトルからオフレゾナンス・スペクトルを差引いて得た。U-5fスペクトルは、フェルミ・レベル(E(sub F))近くに大きな山を持ち、高結合エネルギー側に長い裾野をひいた特有の三角形状をしており、計算で得た結果と、x=1の場合においてさえ、一致しなかった。また、x=0.1の場合もスペクトルの形状に本質的な変化はなかった。このことは、たとえ試料の基底状態の性質がバンド理論でよく記述出来るとはいえ、これらのスペクトルが主として単一サイトの影響を反映していることを意味する。