Superconducting and magnetic properties of monolayers of Fe-Chalcogenides grown on topological insulators

The discovery of Fe-based superconductors (FeSC) is an important hallmark in the field of superconductivity. It provides the potential route to understanding the microscopic mechanism of unconventional superconductivity in high Tc cuprates because of the analogous phase diagram of both materials featuring an antiferromagneticallyordered parent compound. With regards to stoichiometry, the Fe-chalcogenides (FeCh) are the simplest systems of the different families of FeSC. Moreover, they have recently gained attention due to the observation of superconductivity in monolayer FeSe films grown on SrTiO3.

In this talk, I willpresent spin-polarized scanning tunneling spectroscopy (SP-STS) study of monolayers ofFeSexTe1-x (x = 0, 0.5) films grown on the bulk topological insulators. For the case of FeTe, grown on Bi2Te3, we find an energy gap at the Fermi level indicating superconducting correlations up to T ~ 6 K, in contrast to the non-superconducting bulk FeTe. Here we also see that the gap spatially coexists with bi-collinear antiferromagnetic order. On the other hand we see a fully developed but inhomogeneous gap for the case of FeSe0.5Te0.5 grown on Bi2Se1.2Te1.8. I will conclude explaining the importance of our sample system, which provides an ideal platform to study the unconventional superconductivity in FeCh thinned down to a single monolayer and in close proximity to a topological insulator.