Unusual magneto-transport of YBa 2 Cu 3 O 7− δ films due to the interplay of anisotropy, random disorder and nanoscale periodic pinning
Résumé
We study the general problem of a manifold of interacting elastic lines whose spatial correlations are strongly affected by the competition between random and ordered pinning. This is done through magneto-transport experiments with YBa2Cu3O7−δ thin films that contain a periodic vortex pinning array created via masked ion irradiation, in addition to the native random pinning. The strong field-matching effects we observe suggest the prevalence of periodic pinning, and indicate that at the matching field each vortex line is bound to an artificial pinning site. However, the vortex-glass transition dimensionality—quasi-two dimensional instead of the usual three dimensional—evidences reduced vortex-glass correlations along the vortex line. This is also supported by an unusual angular dependence of the magneto-resistance, which greatly differs from that of Bose-glass systems. A quantitative analysis of the angular magneto-resistance allows us to link this behaviour to the enhancement of the system anisotropy, a collateral effect of the ion irradiation.
Domaines
Matière Condensée [cond-mat]
Origine : Publication financée par une institution
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