  The iron-chalcogenide high temperature superconductor Fe(Se,Te) (FST) has
been reported to exhibit complex magnetic ordering and nontrivial band topology
which may lead to novel superconducting phenomena. However, the recent studies
have so far been largely concentrated on its band and spin structures while its
mesoscopic electronic and magnetic response, crucial for future device
applications, has not been explored experimentally. Here, we used scanning
superconducting quantum interference device microscopy for its sensitivity to
both local diamagnetic susceptibility and current distribution in order to
image the superfluid density and supercurrent in FST. We found that in FST with
10% interstitial Fe, whose magnetic structure was heavily disrupted, bulk
superconductivity was significantly suppressed whereas edge still preserved
strong superconducting diamagnetism. The edge dominantly carried supercurrent
despite of a very long magnetic penetration depth. The temperature dependence
of the superfluid density and supercurrent distribution were distinctively
different between the edge and the bulk. Our Heisenberg modeling showed that
magnetic dopants stabilize anti-ferromagnetic spin correlation along the edge,
which may contribute towards its robust superconductivity. Our observations
hold implication for FST as potential platforms for topological quantum
computation and superconducting spintronics.
