title: Superconductivity-induced re-entrance of the orthorhombic distortion in Ba1-xKxFe2As2.
abstract: Detailed knowledge of the phase diagram and the nature of the competing magnetic and superconducting phases is imperative for a deeper understanding of the physics of iron-based superconductivity. Magnetism in the iron-based superconductors is usually a stripe-type spin-density-wave, which breaks the tetragonal symmetry of the lattice, and is known to compete strongly with superconductivity. Recently, it was found that in some systems an additional spin-density-wave transition occurs, which restores this tetragonal symmetry, however, its interaction with superconductivity remains unclear. Here, using thermodynamic measurements on Ba1-xKxFe2As2 single crystals, we show that the spin-density-wave phase of tetragonal symmetry competes much stronger with superconductivity than the stripe-type spin-density-wave phase, which results in a novel re-entrance of the latter at or slightly below the superconducting transition.
authors.affiliation: Institut für Festkörperphysik, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany.
authors.forename: A E
authors.initials: AE
authors.lastname: Böhmer
authors.affiliation: Institut für Festkörperphysik, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Hardy
authors.affiliation: Institut für Festkörperphysik, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany.
authors.forename: L
authors.initials: L
authors.lastname: Wang
authors.affiliation: Institut für Festkörperphysik, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Wolf
authors.affiliation: Institut für Festkörperphysik, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany.
authors.forename: P
authors.initials: P
authors.lastname: Schweiss
authors.affiliation: Institut für Festkörperphysik, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Meingast