We have performed high-resolution photoemission spectroscopy on newly discovered novel boride compounds, MgB2, La-doped CaB6, and DVB2C2. In MgB2, we observed the superconducting gap of about 4.5 meV with s-wave symmetry. In La-doped CaB 6, we found a 1 eV energy gap at the X point in the Brillouin zone, in contrast with the LDA band calculation but in good agreement with the GW calculation. This requests reexamination of the excitonic-insulator model based on an overlap of an electron and a hole band at the X point. In DVB 2C2, we found two (one electron-like and one hole-like) Fermi surfaces, which are composed of the mixed states of the B2p, C2p and Dy5d orbitals, below the antiferro-quadrupolar-ordering temperature.
|Number of pages||6|
|Journal||journal of the physical society of japan|
|Publication status||Published - 2002 Dec 1|
- Fermi surface
- Photoemission spectroscopy
ASJC Scopus subject areas
- Physics and Astronomy(all)