The magnetic field-temperature phase diagram for vortex dynamics in YBa2Cu3O7 has been extended up to 24 T based on 17O NMR experiments on aligned powders. Both spectrum analysis and spin-spin relaxation experiments indicate that vortices are pinned below a temperature Tp, which for low fields is consistent with Tm, the first order melting transition for clean, untwinned crystals. At high fields 10-24T, Tp is 80 K and field independent. Pinned vortices have a Lorentzian spectral density of field fluctuations with a sharp onset.
ASJC Scopus subject areas
- Physics and Astronomy(all)