What makes the Tc of FeSe/SrTiO3 so high?*
Lee Dung-Haia),b)
       
The proposed high T c structures. (a) FeSe makes interfaces on both sides with STO. Growing this structure by, say, molecular beam epitaxy is very challenging because the required growth temperature of STO can nearly melt FeSe. (b) A bulk crystal in which each FeSe layer is sandwiched between two TiO2 layers. In order to ensure charge transfer it is important to maintain the existence of oxygen vacancies in the TiO2 planes.