Regensburg 2010 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 39: SC: Iron-Based Superconductors - 1111

TT 39.2: Talk

Friday, March 26, 2010, 10:30–10:45, H19

Nature of Magnetism in Iron Pnictides: an ab initio study — •Yu-Zhong Zhang, Ingo Opahle, Harald Jeschke, and Roser Valenti — Goethe-Universität Frankfurt, Max-von-Laue-Straße 1, 60438 Frankfurt am Main, Germany

While it is commonly believed that magnetic-mediate pairing is the source of superconductivity in the iron-based superconductors, the nature of magnetism is still under debate. We apply ab initio molecular dynamics to investigate physical properties of LaOFePn, BaFe₂Pn₂ and LiFePn (Pn = As, Sb), so-called 1111, 122 and 111 compounds, respectively. We find that, with substitution of As by Sb, the stripe-type antiferromagnetic orderings are always enhanced. By calculating Pauli susceptibility, we attribute the enhancement of magnetization to the increase of instability at (π,π) when As is substituted by Sb. Furthermore, we study the magnetic and lattice properties of LaOFePn ( Pn=P, As, Sb, Bi) as well as ScOFeP, ScOFeAs and YOFeP and argue that LaOFeSb would be a candidate for a superconductor with highest transition temperature among the investigated compounds. We further suggest that the absence of antiferromagnetic phase in LaOFeP and the presence in LaOFeAs are due to the competition of instability in Pauli susceptibility between (π,π) and (0,0) and therefore argue that superconductivity can only occur through doping in LaOFeSb.