Intrinsic interfacial van der Waals monolayers and their effect on the high-temperature superconductor FeSe/SrTiO3
- Resource Type
- Authors
- Lian Li; Hunter Sims; Matthew F. Chisholm; Tom Berlijn; Donovan N. Leonard; Sokrates T. Pantelides; Zhuozhi Ge; Valentino R. Cooper; Axiel Yaël Birenbaum
- Source
- Physical Review B. 100
- Subject
- High-temperature superconductivity
Materials science
Condensed matter physics
Fermi surface
02 engineering and technology
Substrate (electronics)
Electronic structure
021001 nanoscience & nanotechnology
01 natural sciences
law.invention
Condensed Matter::Soft Condensed Matter
Condensed Matter::Materials Science
symbols.namesake
law
0103 physical sciences
Monolayer
symbols
Density functional theory
Thin film
van der Waals force
010306 general physics
0210 nano-technology
- Language
- ISSN
- 2469-9969
2469-9950
The sensitive dependence of monolayer materials on their environment often gives rise to unexpected properties. It was recently demonstrated that monolayer FeSe on a ${\mathrm{SrTiO}}_{3}$ substrate exhibits a much higher superconducting critical temperature ${T}_{c}$ than the bulk material. Here, we examine the interfacial structure of FeSe/${\mathrm{SrTiO}}_{3}$ and the effect of an interfacial ${\mathrm{Ti}}_{1+x}{\mathrm{O}}_{2}$ layer on the increased ${T}_{c}$ using a combination of scanning transmission electron microscopy and density functional theory. We find ${\mathrm{Ti}}_{1+x}{\mathrm{O}}_{2}$ 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 can reconstruct the FeSe Fermi surface in a manner consistent with experimental observations. Moreover, the interfacial layer introduces symmetry-breaking distortions in the FeSe film that may 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.