Synthesis, characterization, Hall effect and THz conductivity of epitaxial thin films of Fe chalcogenide superconductors

Method of synthesis of high-quality thin films of Fe chalcogenides, Fe(Te,Se) and FeSe is studied. By investigating the correlation between Tc and structural parameters, it is concluded that a compressive strain is introduced on the films on CaF2 substrate, which leads to an increase of Tc than on oxide substrates. Properties both in the normal state and in the superconducting state are measured. Results are discussed in terms of the possibility of further increasing Tc of this material.