Vortex dynamics in single-crystal YBa{sub 2}Cu{sub 3}O{sub 7} probed by {sup 63}Cu nuclear spin echo measurements in the presence of transport current pulses
- Department of Physics, The Ohio State University, 174 West 18th Avenue, Columbus, Ohio 43210 (United States)
We report {sup 63}Cu NMR spin-echo experiments on a high-quality single crystal of YBa{sub 2}Cu{sub 3}O{sub 7} ({ital T}{sub {ital c}}=93 K), to which we have bonded leads for both transport current pulse applications and four-point resistance measurements. For a 9 T field with {ital H}{sub 0} parallel to {ital c}, the resistive transition onsets at 90 K, and {ital R} fully reaches zero at {ital T}{sub {ital R}=0}=76 K. The superconducting state NMR linewidth, however, does not exceed the normal-state value until {ital T}{lt}{ital T}{sub {ital R}=0}, where it is in agreement with predictions based on measured penetration depths. We discuss the possibility that a vortex liquid is present within the resistive transition, with vortex diffusion occurring at a rate fast enough to induce motional narrowing of the vortex lattice contribution to the NMR linewidth. We use the Einstein relation to show that this rapid vortex diffusion implies an upper bound for the correlation length for vortex motion. Inclusion of transport current pulses in the spin-echo pulse sequence is found to have no effect on the magnitude of the spin-echo signal for {ital T} both greater and less than {ital T}{sub {ital R}=0}.
- Research Organization:
- Purdue Univ., West Lafayette, IN (United States)
- DOE Contract Number:
- FG02-90ER45427
- OSTI ID:
- 249444
- Journal Information:
- Physical Review, B: Condensed Matter, Vol. 52, Issue 13; Other Information: PBD: 1 Oct 1995
- Country of Publication:
- United States
- Language:
- English
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