Soft x-ray spectroscopy experiments on the near K-edge of B in MB2 (M=Mg, Al, Ta, and Nb)

Abstract

Soft X-ray absorption and emission measurements are performed for the K- edge of B in MB${}_2$ (M=Mg, Al, Ta and Nb). Unique feature of MgB${}_2$ with a high density of B 2$p_{xy}(\sigma )$-state below and above the Fermi edge, which extends to 1 eV above the edge, is confirmed. In contrast, the B 2$p$ density of states in AlB${}_2$ and TaB${}_2$, 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 $p\sigma$-character in XES and XAS of AlB${}_2$, which is due to the increase of three dimensionality in the $p\sigma$-band in AlB${}_2$. The DOS of NbB${}_2$ has a dip just below the Fermi energy. The present results indicate that the large DOS of B-2$p\sigma$ states near the Fermi energy are crucial for the superconductivity of MgB${}_2$.

3 pages text and 4 pages figures. accepted for publication to Phys. Rev. B

References in corpus (9)

• Superconductivity of metallic boron in MgB_2
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• Possible high $T_c$ superconductivity mediated by antiferromagnetic spin fluctuations in systems with Fermi surface pockets
• Soft x-ray spectroscopy measurements of the p-like density of states of B in MgB2 and evidence for surface boron oxides on exposed surfaces

Cited by in corpus (8)

• Review of Transition-Metal Diboride Thin Films
• Electronic structure of MgB${}_2$: X-ray emission and absorption studies
• X-ray photoelectron spectroscopy studies of non-stoichiometric superconducting NbB2+x
• Electronic Structure of B-2$p\sigma$ and $p\pi$ States in MgB${}_2$, AlB${}_2$ and ZrB${}_2$ Single Crystals
• Electronic Structure of B-2p State in AlB2 Single Crystal: Direct Observation ofpσand pπDensity of States
• Mn and Fe Impurities in MgB_{2}
• Electronic structure of single-crystalline Mg${}_x$Al${}_{1-x}$B${}_2$ probed by x-ray diffraction multipole refinements and polarization-dependent x-ray absorption spectroscopy
• Resonant inelastic x-ray scattering (RIXS) spectra of magnesium diboride