Analysis of trapped fluxoids in FeSe0.5Te0.5 thin film deposited on a CaF2 single crystalline substrate by scanning SQUID microscopy

金グラシア, 井上昌睦, 今村和孝, 東川甲平, 木須隆暢（九大）； BRACCINI Valeria, BELLINGERI Emilio, PUTTI Marina （CNR-SPIN Genova）

Abstract:Though the behavior of fluxoids in a mesoscopic scale is one of the most important issues from both fundamental and engineering point of view, it is not yet well clarified in iron-based superconductors. In this study, we carried out direct observation of trapped fluxoids in FeSe0.5Te0.5 epitaxial thin film by use of scanning SQUID microscopy. In-plane penetration depth and its temperature dependence have been estimated from the magnetic image of single fluxoid. This is a unique method which allows us to study local properties using a fluxoid as a probe. From the temperature dependence of superconducting carrier density, we will also discuss paring symmetry and gap structure in the FeSe0.5Te0.5.