Electron-hole counts in Al-substituted MgB2 superconductors from x-ray Raman scattering

A. Mattila; J. A. Soininen; S. Galambosi; T. Pylkkänen; S. Huotari; N. D. Zhigadlo; J. Karpinski; K. Hämäläinen

doi:10.1103/PhysRevB.78.064517

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Electron-hole counts in Al-substituted MgB2 superconductors from x-ray Raman scattering

A. Mattila, J. A. Soininen, S. Galambosi, T. Pylkkänen, S. Huotari, N. D. Zhigadlo, J. Karpinski, K. Hämäläinen

DOI 10.1103/PhysRevB.78.064517 · Physical Review B

T1

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Abstract

We have investigated the electronic structure of Mg0.83Al0.17B2 and MgB2 single crystals using x-ray Raman scattering at the B-K edge. Utilizing the momentum transfer dependence of the scattering process, together with first-principles multiple scattering calculations, we have extracted the site and symmetry projected density of empty B states in Mg0.83Al0.17B2 in the presence of a core hole. In comparison to the density of states for pure MgB2, we find the B-σ-band hole count to decrease at the Fermi level by 35±9%. The π-band hole count is relatively stable with a 4±7% increase compared to MgB2. These results shed light on the role of band filling in lowering the Tc. Our work opens an application area for x-ray Raman scattering and density of states extraction scheme in studies of doped systems.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
Mg0.83Al0.17B2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	28.2	Pressure not reported	unknown
MgB2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	39	Pressure not reported	unknown