Effect of stripe order on the vortex phase transition inLa1.44Nd0.4Sr0.16CuO4 films

Abstract

The vortex phase transition in La1.44Nd0.4Sr0.16CuO4 epitaxial films with different thicknesses under a compressive strainwere studied systematically by measuring the current–voltage (IV) characteristics in magnetic fields perpendicular to theCuO2 planes. For a strongly compressed thin film, in which the static stripe order is destroyed, theIV curves show a good three-dimensional (3D) vortex glass (VG) scaling collapsein various magnetic fields, indicating a 3D VG phase transition. By applyingthe standard scaling procedure to the data of a strain-released thick film withstatic stripe order, neither a 3D nor a quasi-2D VG model works well. Furtherinvestigation shows that, in order to achieve a good scaling collapse, theKosterlitz–Thouless correlation length should be used for the isothermals aboveTg. The scaling ofisothermals below Tg can also be optimized if the VG correlation length and adjusted static critical exponentν are usedwith D = 2 only, indicating that a quasi-2D VG phase might exist. Our findings reveal that the natureof the vortex phase transition is completely altered in the presence of the stripe order.