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Intrinsic interfacial van der Waals monolayers and their effect on the high-temperature superconductor FeSe/SrTiO$_3$
- Publication Year :
- 2018
-
Abstract
- The sensitive dependence of monolayer materials on their environment often gives rise to unexpected properties. It was recently demonstrated that monolayer FeSe on a SrTiO$_3$ substrate exhibits a much higher superconducting critical temperature T$_C$ than the bulk material. Here, we examine the interfacial structure of FeSe / SrTiO$_3$ and the effect of an interfacial Ti$_{1+x}$O$_2$ layer on the increased T$_C$ using a combination of scanning transmission electron microscopy and density functional theory. We find Ti$_{1+x}$O$_2$ forms its own quasi-two-dimensional layer, bonding to both the substrate and the FeSe film by van der Waals interactions. The excess Ti in this layer electron-dopes the FeSe monolayer in agreement with experimental observations. Moreover, the interfacial layer introduces symmetry-breaking distortions in the FeSe film that favor a T$_C$ increase. These results suggest that this common substrate may be functionalized to modify the electronic structure of a variety of thin films and monolayers.<br />10 pages, 4 figures, supplemental materials available upon request
Details
- Language :
- English
- Database :
- OpenAIRE
- Accession number :
- edsair.doi.dedup.....915287e53059f1886fabbf9999d280b9