Vortex-lattice melting in Tl-2212 thin films

✍ Scribed by J.C. Soret; L. Ammor; A. Smina; B. Martinie; J. Lecomte; L. Coudrier; Ch. Gasser; Ch. Simon; S. Flament

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 286 KB
• Volume: 231
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/0921-4534(94)90155-4

✦ Synopsis

A power law, V~I °, between voltage and current is reported in a TI-2212 thin film in a weak magnetic field (up to 300 mT) applied perpendicularly to the layers. We find experimental support for the existence of a phase transition depending on the magnetic field, below the zero magnetic field transition T~o. We discuss these results in terms of a defect-mediated vortex lattice (VL) melting leading to a Berezinskii-Kosterlitz-Thouless transition type. Consistency is found with a logarithmic coupling energy U(r) =A In (r/ro) between VL defects where the unrenormalized interaction constant A ~ T( Too-T)3/2/H and the Abrikosov lattice parameter sets the cutt-off ro.

Voltage (V-l) characteristics ofhigh-T¢ superconductors in an applied magnetic field have been reported extensively to exhibit, below the mean-field transition temperature Too a power law V~ I a [ 1-6 ]. Usually, such behavior has been discussed [1][2][3][4][5][6][7][8] in the terms of the vortex glass theory [9 ], the flux-creep model [ 10], and the Berezinskii-Kosterlitz-Thouless (BKT) vortex-pair excitation theory [ 11,12]. Another approach [ 13 ] is the dislocation-mediated Kosterlitz-Thouless (KT) melting transition [ 14 ] in the two-dimensional (2D) vortex lattice (VL) [ 15 ]. In this model built on basic ideas of the BKT theory, the solid triangular VL which contains bound pairs of dislocations melts at the BKT transition as these pairs dissociate to create free dislocations.

In this work we report a V-I study carried out in a c oriented TI-2212 micro-bridge. The width and the * Corresponding author.