Vortex dynamics in YBaCuO single crystals with point- and line-like defects-flux creep studies

Studies of vortex dynamics and pinning were conducted in irradiated Y₁Ba₂Cu₃O₇ single crystals by observing the decay of supercurrents with time. The materials contained either point-like defects from proton irradiation or line-like defects from irradiation with energetic heavy ions. Analysis of the first case gives clear support for collective creep theory. With linear defects, the experiments give evidence for thermal smearing of the vortex pinning potential at higher temperatures, as predicted theoretically.     

Magnetic ordering in TmTe

Neutron diffraction experiments were performed on the divalent thulium compound TmTe. Magnetic structure determination leads to a type II antiferromagnet below the Néel temperature T_N = .43 K. No crystal field excitations were observed.