On superconducting and magnetic properties of iron-oxypnictides
V. Barzykin, L. P. Gor'kov*+
Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996 USA
*National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310 USA
+L.D. Landau Institute for Theoretical Physics RAS, 142432 Chernogolovka, Russia
PACS: 74.70.-b, 74.20.-z, 74.20.Rp
Abstract
Pairing symmetry in oxypnictides, a new
family of multiband high-Tc superconductors, is partially imposed by the
positions of multiple Fermi pockets, which itself can give rise to new
order parameters, such as s+,--states or the state of dx2-y2
symmetry. Other pairing states may appear on small pockets for long range
interactions, but they are expected to be sensitive to defects. We identify
the competing antiferromagnetic order with the triplet exciton transition in
the semi-metallic background and discuss whether its coexistence with
superconductivity explains the doping dependence of Tc.