title: Time-reversal symmetry breaking superconductivity in the coexistence phase with magnetism in Fe pnictides.
abstract: We argue that superconductivity in the coexistence region with spin-density-wave (SDW) order in weakly doped Fe pnictides erdiffers qualitatively from the ordinary s(+-) state outside the coexistence region as it develops an additional gap component which is a mixture of intrapocket singlet (s(++)) and interpocket spin-triplet pairings (the t state). The coupling constant for the t channel is proportional to the SDW order and involves interactions that do not contribute to superconductivity outside of the SDW region. We argue that the s(+-)- and t-type superconducting orders coexist at low temperatures, and the relative phase between the two is, in general, different from 0 or π, manifesting explicitly the breaking of the time-reversal symmetry promoted by long-range SDW order. We argue that time reversal may get broken even before true superconductivity develops.
authors.affiliation: Department of Physics, University of Wisconsin, Madison, Wisconsin 53706, USA.
authors.forename: Alberto
authors.initials: A
authors.lastname: Hinojosa
authors.affiliation: School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA.
authors.forename: Rafael M
authors.initials: RM
authors.lastname: Fernandes
authors.affiliation: Department of Physics, University of Wisconsin, Madison, Wisconsin 53706, USA.
authors.forename: Andrey V
authors.initials: AV
authors.lastname: Chubukov
mesh_terms: D058085:Iron Compounds / Q000737:chemistry*; D060328:Magnetic Phenomena; D008280:Magnetics; D008962:Models, Theoretical
chemical_list: D058085:Iron Compounds