Oral: Strain and Interface-Enhanced Superconductivity in FeSe/SrTiO3 bilayer membranes grown by molecular beam epitaxy

Monolayer FeSe grown epitaxially on SrTiO3 (STO) is known to display interface-enhanced superconductivity due to a combination of interface-enhanced electron phonon-coupling and electron doping from the SrTiO3. However, the fixed nature of epitaxial films provides limited opportunities for further tuning the Tc. Here, we demonstrate the synthesis of FeSe/STO bilayer membranes grown by molecular beam epitaxy (MBE), where etch release of the few nanometers thick STO enables continuous tuning of large strains and bending to tune the Se-Fe-Se bond angles. We will report a systematic study on how Tc​ evolves with FeSe and STO membrane thickness, externally applied anisotropic strains, and other structural distortions, benchmarked against predictions from density functional theory and dynamical mean field theory (DFT+eDMFT). DFT+eDMFT study of anisotropic in-plane strain on FeSe predicts that strain can affect the chalcogen angle, suggesting that strain may tune Tc​. Our FeSe/STO membranes provide a highly tunable platform for testing the mechanisms of interface-enhanced superconductivity.