Superconducting dome in homoepitaxial Strontium Titanate thin films

In this work, we studied carrier density dependence of superconductivity in a two-dimensional electron gas (2DEG) in SrTiO₃. The 2DEG is defined in a SrTiO₃ thin film grown homoepitaxially on a SrTiO₃ substrate by molecular beam epitaxy. We systematically explored the superconducting dome in this system by tuning ionic liquid gate voltage. We found superconducting transitions up to 503 mK near an optimal electron density of approximately 3 x 10¹³ cm^-2. This is an increase from the typical optimal transition near 350 mK at two-dimensional interfaces and surfaces of SrTiO₃ single crystal substrates. With measurements in a two-axis vector magnet, we mapped correlations between critical superconducting temperature, coherence length, 2DEG thickness, and electron mean free path.