205Tl NMR study of vortex state of Tl2Ba2CuO6+δ
Abstract We report a 205 Tl NMR study of vortex state for an oriented polycrystalline sample of an overdoped high- T c superconductor Tl 2 Ba 2 CuO 6+δ ( T c ∼85 K) with magnetic field 2 T along the c -axis. An obvious Redfield pattern of the 205 Tl NMR spectrum for our sample at T =5 K indicates the vortex lattice state without local antiferromagnetic order at vortex cores. We emphasize that nonexponential nuclear spin-lattice relaxation curves indicate an imperfect vortex lattice or Bragg glass phase.
Ag-added Y–Ba–Cu–O bulk superconductors were joined using Ag-added Er–Ba–Cu–O solder and different Er211 contents. Microstructural analysis revealed that the volume fraction of Er211 at the joint with a composition of Er123:Er211 = 4:1 was the same as that for the expected volume fraction of the initial composition. That is, this composition seems to be optimum, since the mass balance was maintained during the crystal growth from the initial growth stage to the final stage. The trapped-field distribution for the joint using this composition was uniform and the only single peak indicated that strong coupling was achieved.