Electronic structure of single-crystalline Mg(x)Al(1-x)B(2)

TL;DR

This study investigates the electronic structure of Mg(x)Al(1-x)B(2) single crystals using polarization-dependent x-ray absorption spectroscopy, highlighting the role of in-plane spectral features in superconductivity.

Contribution

It provides experimental evidence linking in-plane electronic spectral features crossing the Fermi level to superconductivity in Mg-Al diborides, supported by theoretical calculations.

Findings

Anisotropic electronic structure near Fermi energy.

In-plane spectral feature crossing E_F correlates with superconductivity.

Good agreement with LDA band structure calculations.

Abstract

Polarization-dependent x-ray absorption spectroscopy at the B 1s edge of single-crystalline Mg(x)Al(1-x)B(2) reveals a strongly anisotropic electronic structure near the Fermi energy. Comparing spectra for superconducting compounds (x=0.9, 1.0) with those for the non-superconductor x=0.0 gives direct evidence on the importance of an in-plane spectral feature crossing E_F for the superconducting properties of the diborides. Good agreement is found with the projected B 2p density of states from LDA band structure calculations.