Berlin 2005 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 23: Posters Superconductivity, Solids at Low Temperature
TT 23.31: Poster
Montag, 7. März 2005, 14:00–18:00, Poster TU D
Electronic structure and electron phonon coupling in Sc doped MgB2 — •Vivien Petzold and Helge Rosner — MPI for Chemical Physics of Solids
Recently, Agrestini et al. reported a detailed study of the effects of Sc substitution in Mg1−xScxB2 [1]. For the achievable Sc doping levels (x=0.12...0.27), the compound shows only a very small lattice expansion, allowing this way the separation of lattice and doping effects on the critical temperature Tc(x) and on the frequency ωE2g of the E2g phonon. To investigate the influence of the Sc concentration x on the electronic properties, we present band structure calculations using different levels of approximation: rigid band and virtual crystal approach as well as supercell calculations and coherent potential approximation. We show that the latter two lead to consistent results with respect to lattice expansion and electronic properties (density of states, Fermi surfaces). We demonstrate that the doping dependent changes in the electronic structure are strongly influenced by the sp2(B)-d(Sc) hybridization. The dependence of the electronic topological transition proposed by Agrestini et al.[1] from the Sc concentration is discussed.
[1] Agrestini et al. Phys. Rev. B 70 134514 (2004).