Vortex matter in the type-II superconductor La3Ni2B2N3−x in the light of NMR
| Autor: | Martin W Pieper, Herwig Michor, Michael Reissner, Tahir Ali |
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| Jazyk: | angličtina |
| Rok vydání: | 2013 |
| Předmět: | |
| Zdroj: | New Journal of Physics, Vol 15, Iss 5, p 053028 (2013) |
| Druh dokumentu: | article |
| ISSN: | 1367-2630 10322264 |
| DOI: | 10.1088/1367-2630/15/5/053028 |
| Popis: | A quantitative analysis of spin-echo NMR measurements of the local field distribution and the spin–spin relaxation time T _2 in the field-cooled superconducting state of the type-II superconductor La _3 Ni _2 B _2 N _3− _x shows evidence for two fluctuation modes of the weakly pinned vortex matter dominating T _2 at different temperatures: long wavelength diffusive modes in the vortex solid at low temperature, and plastic deformation of the viscous liquid close to the critical temperature T _c , with a broad crossover region in between where a more complex theory is required. We determine the melting temperature T _m = 11.5 K of the vortex matter as the temperature where the characteristic time of the plastic deformation slows down to the time scale set by the spin-echo experiment. This is preferred to the conventional estimates from a Lindemann criterion for the melting vortex solid since the quantitative description of T _2 near T _m by the viscous vortex liquid appears to be more consistent. It indicates that the plastic deformation mode might be important for T _2 in the mixed state of other type-II superconductors in the weak pinning regime near T _c as well. |
| Databáze: | Directory of Open Access Journals |
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