Effective Magnetic Field Dependence of the Flux Pinning Energy in FeSe0.5Te0.5 Superconductor

Abstract

The role of a layered structure in superconducting pinning properties is still at a debate. The effects of the vortex shape, which can assume for example a staircase form, could influence the interplay with extrinsic pinning coming from the specific defects of the material, thus inducing an effective magnetic field dependence. To enlighten this role, we analysed the angular dependence of flux pinning energy U(H,θ) as a function of magnetic field in FeSe0.5Te0.5 thin film by considering the field components along the ab-plane of the crystal structure and the c-axis direction. U(H,θ) has been evaluated from magneto-resistivity measurements acquired at different orientations between the applied field up to 16 T and FeSe0.5Te0.5 thin films grown on a CaF2 substrate. We observed that the U(H,θ) shows an anisotropic trend as a function of both the intensity and the direction of the applied field. Such a behaviour can be correlated to the presence of extended defects elongated in the ab-planes, thus mimicking a layered superconductor, as we observed in the microstructure of the compound. The comparison of FeSe0.5Te0.5 with other superconducting materials provides a more general understanding on the flux pinning energy in layered superconductors.

Unveiling intrinsic material and extrinsic pinning dimensionality in superconductors: Why Fe(Se,Te) is able to mimic YBCO

“…In our previous studies, we focused mostly on the structural properties of the sample, while the chemical composition was investigated only to a limited extent. Specifically, in our recent works, 42 , 43 the main results were related to the microstructure of the material, revealing ab elongated domains interconnected by means of grain boundaries, while the chemical variation was only qualitatively assessed. Here, we used a ternary phase diagram to identify two distinct chemical phases within the sample, which could not be resolved based only on the STEM imaging and EELS elemental mapping alone.…”