Title: Electronic coupling between a FeSe monolayer film and ${\mathrm{SrTiO}}_3$ substrate

Abstract

Several experimental groups have reported superconductivity in single unit cell layers of FeSe on SrTiO₃ and a few other substrates, with critical temperature $$T_c$$ reports ranging up to 100 K, and a variety of theoretical work has been done. In this work we examine more closely the interaction of a single FeSe layer with a TiO₂ terminated SrTiO₃(001) (STO) substrate. Several situations are analyzed: the underlying ideal interface, the effect of zpolarized longitudinal optic [LO($$\hat{z}$$)] phonons in STO, electron doping of the STO substrate, substitution of Se by the bordering chalcogenides S and Te, and doping by adsorption of K on the FeSe surface. These results complement earlier studies of O and Se vacancies. The O p_y, p_y surface band of STO persists at the interface, and by sharing holes with the hole pocket of FeSe it plays a part in the behavior around the interface, initially by determining the Fe Fermi level lineup with the STO band gap. The LO($$\hat{z}$$) mode causes strong band shifts around the interface but the strength of coupling to the Fe bands cannot be obtained with our methods. Adsorption of 25% K (one K per four Fe) fills the small O interface hole pocket and donates the rest of the electrons to the Fe hole pockets, filling them.

Authors:

Huang, Y. N. ^[1]; Pickett, W. E. ^[2]

---

+ Show Author Affiliations

1. Chinese Academy of Sciences (CAS), Beijing (China). Key Lab. of Materials Physics; Univ. of Science and Technology of China, Hefei (China); Univ. of California, Davis, CA (United States). Dept. of Physics
2. Univ. of California, Davis, CA (United States). Dept. of Physics

Publication Date:

Wed Apr 05 00:00:00 EDT 2017

Research Org.:

Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). National Energy Research Scientific Computing Center (NERSC)

Sponsoring Org.:

USDOE Office of Science (SC); China Scholarship Council (CSC); National Science Foundation (NSF)

OSTI Identifier:

1544398

Alternate Identifier(s):

OSTI ID: 1349961

Grant/Contract Number:  

AC02-05CH11231; DMR 1607139

Resource Type:

Accepted Manuscript

Journal Name:

Physical Review B

Additional Journal Information:

Journal Volume: 95; Journal Issue: 16; Journal ID: ISSN 2469-9950

Publisher:

American Physical Society (APS)

Country of Publication:

United States

Language:

English

Subject:

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY