Jiang, W. and Yeh, N.-C. and Tombrello, T. A. and Rice, A. P. and Holtzberg, F. (1997) Current-driven vortex dynamics in untwinned superconducting single crystals. Journal of Physics: Condensed Matter, 9 (38). pp. 8085-8100. ISSN 0953-8984. http://resolver.caltech.edu/CaltechAUTHORS:JIAjpcm97
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Current-driven vortex dynamics of type-II superconductors in the weak-pinning limit is investigated by quantitatively studying the current-dependent vortex dissipation of an untwinned YBa2Cu3O7 single crystal. For applied current densities (J) substantially larger than the critical current density (Jc), non-linear resistive peaks appear below the thermodynamic first-order vortex-lattice melting transition temperature (Tm), in contrast to the resistive hysteresis in the low-current limit (J < Jc). These resistive peaks are quantitatively analysed in terms of the current-driven coherent and plastic motion of vortex bundles in the vortex-solid phase, and the non-linear current - voltage characteristics are found to be consistent with the collective flux-creep model. The effects of high-density random point defects on the vortex dynamics are also investigated via proton irradiation of the same single crystal. Neither resistive hysteresis at low currents nor peak effects at high currents are found after the irradiation. Furthermore, the current-voltage characteristics within the instrumental resolution become completely ohmic over a wide range of currents and temperatures, despite theoretical predictions of much larger Jc-values for the given experimental variables. This finding suggests that the vortex-glass phase, a theoretically proposed low-temperature vortex state which is stabilized by point disorder and has a vanishing resistivity, may become unstable under applied currents significantly smaller than the theoretically predicted Jc. More investigation appears necessary in order to resolve this puzzling issue.
|Additional Information:||© 1997 Institute of Physics Received 10 January 1997, in final form 1 July 1997, Print publication: Issue 38 (22 September 1997) The authors are grateful to Dr V M Vinokur, Dr A V Samoilov and Dr M Konczykowski for useful discussions. This work was jointly supported by NSF Grants No DMR-9401315 and No DMR93-18931, ONR Grant No N00014-91-J-1556, the David and Lucile Packard Foundation, and NASA.|
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|Deposited On:||19 Feb 2006|
|Last Modified:||26 Dec 2012 08:46|
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