  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.

Superconductivity