%0 Journal Article
%A Sefrioui, Zouhair
%A Arias Serna, Diego
%A Morales, F.
%A Varela del Arco, María
%A León Yebra, Carlos
%A Escudero, R.
%A Santamaría Sánchez-Barriga, Jacobo
%T Evidence for vortex tunnel dissipation in deoxygenated YBa_(2)Cu_(3)O_(6.4) thin films
%D 2001
%@ 0163-1829
%U https://hdl.handle.net/20.500.14352/59642
%X We report on transport and magnetic relaxation measurements of deoxygenated YBa_(2)Cu_(3)O_(7-δ) thin films. Strongly oxygen depleted samples with δ=0.6 are produced to ensure the pure two-dimensional nature of the vortex system. Linear resistivity shows a temperature dependence according to      ρ_(lin^(α))exp[-((T_(0)/T)^(p)]. T_(0) takes a value of 230±10 K over the whole field range, and p changes from 1±0.03 at 2 T to 0.70±0.03 at 8 T. For fields higher than 4 T, dissipation in the linear regime (low current densities) is dominated by quantum variable range hopping ~VRH! of vortices. At high current densities and low temperatures, nonlinear dissipation takes place by quantum creep, characterized by a temperature-independent resistivity and by a saturation of the magnetic relaxation rate.
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