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



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


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 MgB2. 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 pxpy symmetry. Our observations are consistent with several electronic structure calculations reporting a narrow energy window of empty pxPy states that has fallen to zero at 0.8 eV above the Fermi level. The disappearance of the px py feature in EELS spectra from grain boundaries suggests that this signature may become powerful in probing the superconducting properties at the nanoscale.
Physical Review Letters
No. 24


electron energy loss spectroscopy (EELS), fermi level, k-edge, p<sub>x</sub>p<sub>y</sub>, x-ray absorption spectroscopy (XAS)


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 MgB<sub>2</sub> Superconductor, Physical Review Letters (Accessed April 16, 2024)
Created May 31, 2002, Updated October 12, 2021