Europhys. Lett.
Volume 48, Number 6, December 1999
Page(s) 679 - 685
Section Condensed matter: electronic structure, electrical, magnetic and optical properties
Published online 01 September 2002
DOI: 10.1209/epl/i1999-00538-7

Europhys. Lett, 48 (6), pp. 679-685 (1999)

Pure 2D vortex-glass phase transition with $T_{\rm g} = {\rm0\;K}$in deoxygenated $\rm YBa_2Cu_3O_{6.4}$ thin films

Z. Sefrioui 1, D. Arias 1, M. Varela 2, M. A. López de la Torre 3, C. León 1
G. D. Loos 1 and J. Santamaría 1

1Departamento de Física Aplicada III, Universidad Complutense de Madrid
28040, Madrid, Spain
2Departamento de Física, Universidad Carlos III de Madrid
Leganés 28911, Madrid, Spain
3Departamento de Física Aplicada, Universidad de Castilla-La Mancha
13071 Ciudad Real, Spain

(received 14 July 1999; accepted in final form 19 October 1999)

PACS. 74.60Ge - Flux pinning, flux creep, and flux-line lattice dynamics.
PACS. 74.60Jg - Critical currents.
PACS. 74.72Fq - Tl-based cuprates.


Non-linear I-V characteristics have been measured on high-quality deoxygenated $\rm YBa_2Cu_3O_{6.4}$ thin films, in magnetic fields up to $\rm 8\;T$. Critical scaling analysis of the current-voltage data demonstrates the existence of a pure two-dimensional vortex-glass transition with $T_{\rm g} = 0$ for high magnetic fields (7, $\rm 8\;T$). The validity of the pure 2D vortex-glass model in our samples is checked with the linear resistivity term and the non-linear current density. The linear resistivity $\rho_{\rm lin}(T) \propto \exp[-(T_0/T)^p]$ from resistivity vs. temperature and current-voltage measurements, produces the parameters p (p = 0.78 for $H =
{\rm 7\;T}$, p = 0.73 for $H = {\rm 8\;T}$) and T0 (230 K) used for the scaling analysis. The non-linear current density $j_{\rm nl}$ exhibits a power law temperature dependence $j_{\rm nl} (T) \propto T^3$ suggesting $\nu_{\rm 2D} = 2$ as predicted by the 2D vortex-glass theory. The values of the exponent p obtained in this study are in good agreement with the predictions of the quantum theory of vortex tunneling.


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