title: Superconducting state in SrFe2-xCoxAs2 by internal doping of the iron arsenide layers.
abstract: In the strontium iron-cobalt arsenides SrFe2-xCoxAs2 (0.2 < or = x < or = 0.4) superconductivity with T_{c} up to 20 K is observed in magnetic susceptibility, electrical resistivity, and specific heat data. This first observation of bulk superconductivity induced by electron doping in this family of compounds-despite strong disorder in the Fe-As layer-favors an itinerant electronic theory in contrast to the strongly correlated cuprates and renders a p- or d-wave pairing unlikely. The magnetic ordering present in SrFe2As2 is rapidly suppressed by substitution of Fe by Co. Density functional theory calculations show that this is due to a rigid downshift of the Fe-3d_{x;{2}-y;{2}}-related band edge in the density of states.
authors.affiliation: Max-Planck-Institut für Chemische Physik fester Stoffe, Nöthnitzer Strasse 40, 01187 Dresden, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Leithe-Jasper
authors.forename: W
authors.initials: W
authors.lastname: Schnelle
authors.forename: C
authors.initials: C
authors.lastname: Geibel
authors.forename: H
authors.initials: H
authors.lastname: Rosner