Interdependence of magnetism and superconductivity in the borocarbide TmNi2B2C
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).
Norgaard
K
Condensed Matter Physics and Chemistry Department, Riso National Laboratory, DK-4000 Roskilde, Denmark.
Eskildsen
MR
Andersen
NH
Jensen
J
Hedegard
P
Klausen
SN
Canfield
PC