Interface induced high temperature superconductivity in single unit-cell FeSe films on SrTiO3(110)

Abstract: We report high temperature superconductivity in one unit-cell (1-UC) FeSe films grown on STO(110) substrate by molecular beam epitaxy. By in-situ scanning tunneling spectroscopy measurement, we observed a superconducting gap as large as 17 meV. Transport measurements on 1-UC FeSe/STO(110) capped with FeTe layers reveal superconductivity with an onset TC of 31.6 K and an upper critical magnetic field of 30.2 T. We also find that the TC can be further increased by an external electric field, but the effect is smaller than that on STO(001) substrate. The study points out the important roles of interface related charge transfer and electron-phonon coupling in the high temperature superconductivity of FeSe/STO.