Abstract
The magnetic field–temperature phase diagram for vortex dynamics in has been extended up to 24 T based on NMR experiments on aligned powders. Both spectrum analysis and spin-spin relaxation experiments indicate that vortices are pinned below a temperature , which for low fields is consistent with , the first order melting transition for clean, untwinned crystals. At high fields 10–24 T, is 80 K and field independent. Pinned vortices have a Lorentzian spectral density of field fluctuations with a sharp onset.
- Received 22 August 1997
DOI:https://doi.org/10.1103/PhysRevLett.80.1726
©1998 American Physical Society