%0 Journal Article
%A Sefrioui, Zouhair
%A Arias, D.
%A González Herrera, Elvira María
%A León, C.
%A Santamaría Sánchez-Barriga, Jacobo
%A Vicent López, José Luis
%T Vortex liquid entanglement in irradiated YBa_2Cu_3O_7 thin films
%D 2001
%@ 1098-0121
%U https://hdl.handle.net/20.500.14352/60176
%X Epitaxial YBa_2Cu_3O_7 thin films, grown by high-pressure de sputtering, an irradiated with He^(+) ions at 80 keV with doses between 10_(14) and 10_(15) cm^(-2). Irradiation reduces the critical temperature but it does not modify the carrier concentration. Angle- dependent resistivity is used to show that the mass anisotropy does not change upon irradiation. The melting transition in magnetic fields applied parallel to the c axis is analyzed by I-V critical scaling, and all irradiated and nonirradiated samples show a three- dimensional vortex glass transition with the same critical exponents. The dissipation in the liquid state is analyzed in terms of the activation energy of the magnetoresistance in a perpendicular magnetic field. While as-grown samples show an activation energy depending as 1/H on the applied magnetic field, irradiated samples show a dependence as 1/H^(0.5), characteristic of plastic deformation of vortices. This is discussed in terms of the point  disorder introduced by ion irradiation.
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