Sefrioui, ZouhairArias, D.González Herrera, Elvira MaríaLeón, C.Santamaría Sánchez-Barriga, JacoboVicent López, José Luis2023-06-202023-06-202001-02-011098-012110.1103/PhysRevB.63.064503https://hdl.handle.net/20.500.14352/60176©2001 The American Physical Society. Financial support from CICYT Grant Nos. MAT94-0604, MAT97-0675, and MAT99-1706E is acknowledged. Z.S. thanks AECI for financial support.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.engjournal articlehttp://dx.doi.org/10.1103/PhysRevB.63.064503https://journals.aps.orgopen access538.9539.1High-temperature SuperconductorsHigh-tc superconductorsLattice-melting transitionFlux-line-latticeII SuperconductorsQuenched disorderPhase-transitionsGlass-transitionSingle-crystalsElastic theoryElectricidadElectromagnetismoFísica de materialesFísica del estado sólido2202.03 Electricidad2202 Electromagnetismo2211 Física del Estado Sólido