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TT: Fachverband Tiefe Temperaturen

TT 27: SC: Fe-based Superconductors - LiFeAs

TT 27.4: Vortrag

Dienstag, 15. März 2011, 14:45–15:00, HSZ 304

Theory for Magnetism and Triplet Superconductivity in LiFeAs — Philip Brydon¹, •Maria Daghofer², Carsten Timm¹, and Jeroen van den Brink² — ¹Institut für Theoretische Physik, TU Dresden — ²IFW Dresden

Superconducting pnictides are spin-singlet superconductors, where superconductivity is found near an antiferromagnetic (AF) phase. The AF order is believed to be largely driven by Fermi surface nesting. The band structure of LiFeAs, which does not have to be doped to become superconducting, differs from the other pnictides by two distinct features; it shows poorer nesting and has hole pockets that are much more shallow than he electron pockets. We incorporate these specific features into a three-band model and study the resulting magnetic order and pairing instabilities. We find that they are markedly different from the results for models with better nesting. The magnetic susceptibility shows a peculiar ring-shaped feature around (0,0) instead of peaks at (π,0) and (0,π), as one would expect in the AF phase. These "almost FM" fluctuations are found to promote triplet superconductivity with a p-wave symmetry.