Unraveling the Symmetry of the Hole States Near the Fermi Level in the MgB2 Superconductor

Published

June 1, 2002

Author(s)

Y Zhu, A R. Moodenbaugh, G Schneider, J W. Davenport, T Vogt, Q Li, G Gu, Daniel A. Fischer, J Tafto

Abstract

We use x-ray absorption spectroscopy (XAS) and electron energy loss spectroscopy (EELS) to study the near edge fine structure at the K-edge of boron in the superconductor M_gB₂. We observe in XAS a peak of width 0.6 eV at the threshold of this K-edge, signaling a narrow energy region with empty boron p-states near the Fermi level. Comparison of EELS spectra with momentum transfer parallel and perpendicular to the a-b planes shows that these states have p_xp_y symmetry. Our observations are consistent with several electronic structure calculations reporting a narrow energy window of empty p_xP_y states that has fallen to zero at 0.8 eV above the Fermi level. The disappearance of the p_x p_y feature in EELS spectra from grain boundaries suggests that this signature may become powerful in probing the superconducting properties at the nanoscale.

Citation

Physical Review Letters

Volume

88

Issue

No. 24

Pub Type

Journals

Keywords

electron energy loss spectroscopy (EELS), fermi level, k-edge, p_xp_y, x-ray absorption spectroscopy (XAS)

Citation

Zhu, Y. , Moodenbaugh, A. , Schneider, G. , Davenport, J. , Vogt, T. , Li, Q. , Gu, G. , Fischer, D. and Tafto, J. (2002), Unraveling the Symmetry of the Hole States Near the Fermi Level in the MgB₂ Superconductor, Physical Review Letters (Accessed April 19, 2024)