Technical Report of ISSP Ser. A: Number 3048

Abstract

The B2p- and C2p-projected partial density of states of the superconductor YNi2B2C and nonsuperconducting metal LaNi2B2C were studied by the BK- and CK-Soft X-ray Emission Spectroscopy (SXES). The photoemission spectra, corresponding to the Ni3d-projected partial density of states, were also measured to compare with both SXES. The clear Fermi edges were found in BK-SXES and photoemission spectra. The Fermi edge intensity of YNi2B2C is higher than that of LaNi2B2C in the BK-SXES. The spectral features of B2p- and C2p-valence bands including the Fermi edges are quite well consistent with the band calculation, though the electron correlation effect is significant for Ni3d band. The absorption spectra suggest that Fermi level lies around the maximum of the B2p-conduction band for YNi2B2C, while it is located at the lower energy side of this conduction band for LaNi2B2C.

超伝導体YNi2B2Cおよび非超伝導金属LaNi2B2CのB2pおよびC2p放射部分状態密度をBKおよびCK軟X線放射スペクトロスコピー(SXES)によって調べた。両SXESを比較するために、Ni3d放射部分状態密度に対応する光電子放出スペクトルも測定した。BKのSXESと光電子放出スペクトルには明確なフェルミエッジが見られた。YNi2B2Cのフェルミエッジ強度はBKのSXESにおけるLaNi2B2Cの強度より大きい。電子相関効果はNi3dバンドに対して重要であるにもかかわらず、フェルミエッジを含むB2pおよびC2p原子価バンドのスペクトル特性はバンド計算値とよく一致している。吸収スペクトルは、フェルミ準位がYNi2B2CのB2p伝導バンドの最大値周辺にあるが、LaNa2B2Cの場合、フェルミ準位はB2p伝導バンドの低エネルギー側にあることを示している。