title: Interdependence of magnetism and superconductivity in the borocarbide TmNi2B2C
abstract: We have discovered a new antiferromagnetic phase in TmNi2B2C by neutron diffraction. The ordering vector is Q(A) = (0.48,0,0) and the phase appears above a critical in-plane magnetic field of 0.9 T. The field was applied in order to test the assumption that the zero-field magnetic structure at Q(F) = (0.094,0.094,0) would change into a c-axis ferromagnet if superconductivity were destroyed. We present theoretical calculations which show that two effects are important: a suppression of the ferromagnetic component of the RKKY exchange interaction in the superconducting phase and a reduction of the superconducting condensation energy due to the periodic modulation of the moments at Q(A).
authors.affiliation: Condensed Matter Physics and Chemistry Department, Riso National Laboratory, DK-4000 Roskilde, Denmark.
authors.initials: K
authors.lastname: Norgaard
authors.initials: MR
authors.lastname: Eskildsen
authors.initials: NH
authors.lastname: Andersen
authors.initials: J
authors.lastname: Jensen
authors.initials: P
authors.lastname: Hedegard
authors.initials: SN
authors.lastname: Klausen
authors.initials: PC
authors.lastname: Canfield