Influence of a magnetic field on the antiferromagnetic order in UPt_3
  A neutron diffraction experiment was performed to investigate the effect of a magnetic field on the antiferromagnetic order in the heavy fermion superconductor UPt_3. Our results show that a field in the basal plane of up to 3.2 Tesla, higher than H_c2(0), has no effect: it can neither select a domain nor rotate the moment. This has a direct impact on current theories for the superconducting phase diagram based on a coupling to the magnetic order. 
B. Lussier (McGill University), L. Taillefer (McGill University),   W.J.L. Buyers (Chalk River), T.E. Mason (University of T...