Molecular Beam Epitaxy Growth of FeSe/SrTiO₃ Heterostructures

Monolayer of FeSe grown on SrTiO₃ surface has shown to exhibit a large increase in superconducting transition temperature, from ~8K in bulk FeSe to above 100K (Ge J, et al. Nature Materials 14, 285-289(2015) ). Extensive studies performed on this system to date suggested that both electronic and phononic mechanism might be responsible for this enhancement of superconductivity. Therefore, a route towards increasing the Tc even further might involve using oxide substrates with carefully engineered chemical composition. We use molecular beam epitaxy to grow thin film SrTiO₃ on commercial substrates with a precise control of the surface termination (SrO vs. TiO₂). Furthermore, we discuss our preliminary results on comparing the structural and electronic properties of FeSe deposited on SrTiO₃ thin films and bulk commercial substrates.