2001/08/15 by J. Nakamura, Jin Nakamura, Nobuyoshi Yamada +8 · 2 citations
Engineering · Materials Science · Physics and Astronomy · #Boron and Carbon Nanomaterials Research #Silicon Carbide Semiconductor Technologies #Superconductivity in MgB2 and Alloys #cond-mat.supr-con
paper · pdf · doi:10.1103/physrevb.64.174504
3 pages text and 4 pages figures. accepted for publication to Phys. Rev. B
arxiv created 2001/08/15 · openalex publication_date 2001/10/03 · arxiv updated 2009/11/30 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
Soft x-ray-absorption and emission measurements are performed for the K-edge of B in MB2 (M=Mg, Al, Ta, and Nb). Unique feature of MgB2 with a high density of the B 2pxy(\ensuremathσ) state below and above the Fermi edge, which extends to 1 eV above the edge, is confirmed. In contrast, the B 2p density of states in AlB2 and TaB2, both of occupied and unoccupied states, decreased linearly towards the Fermi energy and showed a dip at the Fermi energy. Furthermore, there is a broadening of the peaks with p\ensuremathσ character in x-ray emission spectra and x-ray-absorption sepctra of AlB2, which is due to the increase of three dimensionality in the p\ensuremathσ band in AlB2. The density of states (DOS) of NbB2 has a dip just below the Fermi energy. The present results indicate that the large DOS of B\ensuremath-2p\ensuremathσ states near the Fermi energy are crucial for the superconductivity of MgB2.