Electronic Structure of B-2pState in AlB₂Single Crystal: Direct Observation ofpσ andpπ Density of States

Abstract

X-ray emission (XES) and absorption (XAS) spectra near the B-K edge were measured on single-crystalline AlB2 compound which is an isostructural diboride of superconducting MgB2. The partial density of states (PDOS) of B-2pσ and pπ orbitals were derived from the polarization dependence of XES and XAS spectra. There are considerable amounts of PDOS near the Fermi energy in AlB2 similarly to that in MgB2, but there are almost no PDOS in pσ orbitals of AlB2 near the Fermi energy, i.e., a pseudo-gap in pσ state and a broad metallic state in pπ state are observed. The present result indirectly supports scenarios that the pσ holes play an important role in the occurrence of superconductivity in MgB2. The overall features of PDOS were found to be in good agreement with the result of band calculation of AlB2, but a small discrepancy in the Fermi energy is observed, which is attributed to the Al vacancy in the compounds, i.e., the estimated concentration is Al0.93B2. KEYWORDS: MgB 2 , AlB 2 , single crystal, partial density of state, pσ and pπ orbitals, X-ray emission and absorption spectroscopy

On the electronic and structural properties of aluminum diboride Al0.9B2

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Holes in the Valence Band of Superconducting Boron-Doped Diamond Film Studied by Soft X-ray Absorption and Emission Spectroscopy

“…As the dipole selection rule between the 1s core level and the 2p state governs the transition, we can obtain the partial density of states (PDOS) of carbon 2p and of boron 2p separately, which can give important information on the mechanism of superconductivity. [10,11,12] Moreover, XES spectroscopy is a bulk sensitive probe, not a surface sensitive one like photoelectron spectroscopy.…”

Interaction of Boron Nitride Nanotubes with Aluminum: A Computational Study

“…In terms of both charge distribution and bond lengths, the binding tended to be more localized on one of the three nearest B atoms, rather than being equally shared as in the Al–N 3 type of structure. This is more characteristic of a covalent bond formation, as found in the AlB 2 crystalline compound …”

“…This is more characteristic of a covalent bond formation, as found in the AlB 2 crystalline compound. 50 The case of an Al 4 cluster adsorbed on the h-BN sheet with an N-vacancy is presented in Figure 6. Similarly to adsorption on the sheet with a B-vacancy, there were three possible adsorption configurations found, which, following the nomenclature defined above, were indicated as N2, N3-60, and N3-120 (Figure 6, parts a, b, and c).…”