title: Evidence for a magnetically driven superconducting Q phase of CeCoIn5.
abstract: We have studied the magnetic order inside the superconducting phase of CeCoIn5 for fields along the [1 0 0] crystallographic direction using neutron diffraction. We find a spin-density wave order with an incommensurate modulation Q=(q,q,1/2) and q=0.45(1), which within our experimental uncertainty is indistinguishable from the spin-density wave found for fields applied along [1 -1 0]. The magnetic order is thus modulated along the lines of nodes of the d{x{2}-y{2}} superconducting order parameter, suggesting that it is driven by the electron nesting along the superconducting line nodes. We postulate that the onset of magnetic order leads to reconstruction of the superconducting gap function and a magnetically induced pair density wave.
authors.affiliation: Laboratory for Developments and Methods, Paul Scherrer Institute, CH-5232 Villigen, Switzerland.
authors.forename: M
authors.initials: M
authors.lastname: Kenzelmann
authors.forename: S
authors.initials: S
authors.lastname: Gerber
authors.forename: N
authors.initials: N
authors.lastname: Egetenmeyer
authors.forename: J L
authors.initials: JL
authors.lastname: Gavilano
authors.forename: Th
authors.initials: T
authors.lastname: Strässle
authors.forename: A D
authors.initials: AD
authors.lastname: Bianchi
authors.forename: E
authors.initials: E
authors.lastname: Ressouche
authors.forename: R
authors.initials: R
authors.lastname: Movshovich
authors.forename: E D
authors.initials: ED
authors.lastname: Bauer
authors.forename: J L
authors.initials: JL
authors.lastname: Sarrao
authors.forename: J D
authors.initials: JD
authors.lastname: Thompson