C. S. Oglesby

Antiferromagnetic order in superconducting UPt3: An x‐ray magnetic scattering study (invited)

The temperature dependence of the antiferromagnetic order in superconducting UPt3 has been measured using x‐ray resonance magnetic scattering. The magnetic Bragg intensity at Q=(1/2,0,2) grows linearly from TN=5 K to T≂0.6 K (TC+=0.53 K), where it becomes suppressed with temperature to a reduction of ∼6% at T=180 mK. These results demonstrate a coupling of the superconducting and antiferromagnetic order parameters and are consistent with a suppression in the magnitude of the ordered moments below Tc when compared with previously obtained neutron‐scattering data.

Small angle neutron scattering from the vortex lattice in 2H‐NbSe2 (invited) (abstract)

We report on small angle neutron scattering studies of the flux‐line lattice in single crystal 2H‐NbSe2. For fields inclined with respect to the c axis, we find distortions and form factors consistent with Ginzburg–Landau corrections to the London equations with a mass anisotropy Γ=10.1±0.9. The flux lattice orientation, however, remains pinned to the crystal lattice for all tilts studied, in disagreement with the orientation defined by anisotropic London theory. For fields below 2 kG parallel to the c axis, the peaks are no longer resolution limited. The correlation lengths extracted are history dependent, and show that the lattice is annealed when a current greater than the critical current is applied. This occurs both when a direct transport current is used, or an induced current in a zero field cooled experiment. The annealing is seen in both the transverse and longitudinal correlation lengths, and calls into question the relationship between the Larkin–Ovchinnikov correlation length and the measured ...