Vortex liquid entanglement in twinnedYBa2Cu3O7

Abstract

The angular dependence of the in-plane resistivity (T,H,) of melt textured YBa 2 Cu 3 O 7 /Y 2 BaCuO 5 composites has been measured in a large range of magnetic fields and temperatures and from them, the intrinsic anisotropy of the superconducting state has been verified following the anisotropic Ginzburg-Landau approach. The influence of correlated defects like twin boundaries and quenched disorder generated by Y 2 BaCuO 5 precipitates on the pinning behavior of these composites in the liquid vortex state is analyzed, and the corresponding phase diagram is determined and compared to that of twinned single crystals. We show that the irreversibility line displays an upwards shift due to twin boundary pinning enabling to define a ''quenched'' Bose glass transition. A new region in the vortex liquid state is identified where twin boundary pinning defines a partially entangled liquid vortex state characterized by a short-range c-axis vortex coherence. The transition to the entangled liquid phase is experimentally determined. The relevance of this depinning line and its unique position with respect to twinned single crystals is discussed. ͓S0163-1829͑99͒01741-5͔

Anisotropy of the low-field critical point of the melting line of twinnedYBa2Cu3OFigueras1, Puig2, Obradors3 et al. 2002Phys. Rev. BSelf Cite3030View full textAdd to dashboardCite

“…4,6,10 It was suggested that H lcp was not modified by twin boundaries but this is an unexpected behavior because twin boundaries lead to a secondorder Bose-glass transition, 11 characterized by a cusp in the ''irreversibility line'' and in the vortex activation energy for magnetic-field orientations close to the c axis. 12,13 This behavior would be also inconsistent with a recent study of the influence on H lcp of linear defects created by ion irradiation. 8 That work showed that H lcp is pushed up while the Boseglass regime develops.…”

Anisotropic Vortex Plasticity in the Liquid State ofYBa2Cu3O7: Evidence

“…These results have allowed us to identify a partially entangled vortex liquid phase in YBa 2 Cu 3 O 7 , when quenched and correlated disorders compete. The main characteristic of this new phase, which was qualitatively claimed in [12,13], is a finite c-axis vortex correlation length. Y123͞211 composites were grown by a modified Bridgman method [10].…”

Vortex liquid entanglement in irradiatedYBa2Cu3O7Sefrioui1, Arias2, González3 et al. 2001Phys. Rev. BSelf Cite434231View full textAdd to dashboardCite

“…The activation energy of the form of U pl , is then a strong indication of vortex entanglement. 30,31,34 Since vortex entanglement involves vortex deformations of size a 0 , and melting involves deformations which are a fraction c L ͑the Lindemann number͒ of the vortex lattice spacing, the basic energy scale governing vortex entanglement (U pl ϳ␥ Ϫ1 ⑀ 0 a 0 ) is the same governing melting. Plastic barriers and melting temperature, T g , can be related via the Lindemann number:…”

“…Additionally, we would like to remark that, besides correlated disorder, there is, most likely, also point disorder present in the nonirradiated samples, and there may be then a complicated interplay between both types of defects. 10,34 In summary, we have studied the effect of light ion irradiation on the dissipation properties of epitaxial YBCO films. The dynamics of the vortex solid to liquid transition seems not to be modified by ion irradiation.…”