Magnetic structure of the noncentrosymmetric heavy-fermion   superconductor CePt3Si
  We have determined the magnetic structure of the noncentrosymmetric heavy-fermion superconductor CePt3Si using elastic polarized neutron scattering with field-projected (longitudinal) XYZ polarization analysis. We find that the magnetic moment has components both in the tetragonal basal plane and along the tetragonal four-fold axis. Such a magnetic structure is not symmetry-allowed if the magnetic phase transition is second order, and may imply that CePt3Si has lower symmetry in the superconducting state than originally thought. 
B. Fak, M. Enderle, G. Lapertot
cond-mat.str-el