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Title: Superconducting proximity effect in a topological insulator using Fe(Te, Se)

Interest in the superconducting proximity effect has recently been reignited by theoretical predictions that it could be used to achieve topological superconductivity. Low- T c superconductors have predominantly been used in this effort, but small energy scales of ~1 meV have hindered the characterization of the emergent electronic phase, limiting it to extremely low temperatures. In this work, we use molecular beam epitaxy to grow topological insulator Bi 2Te 3 in a range of thicknesses on top of a high- T c superconductor Fe(Te,Se). Using scanning tunneling microscopy and spectroscopy, we detect Δ ind as high as ~3.5 meV, which is the largest reported gap induced by proximity to an s -wave superconductor to date. We find that Δ ind decays with Bi 2Te 3 thickness, but remains finite even after the topological surface states have been formed. Finally, by imaging the scattering and interference of surface state electrons, we provide a microscopic visualization of the fully gapped Bi 2Te 3 surface state due to Cooper pairing. Lastly, our results establish Fe-based high- T c superconductors as a promising new platform for realizing high- T c topological superconductivity.
Authors:
 [1] ;  [1] ;  [1] ;  [1] ;  [2] ;  [2] ;  [2] ;  [1] ;  [1]
  1. Boston College, Chestnut Hill, MA (United States). Dept. of Physics
  2. Brookhaven National Lab. (BNL), Upton, NY (United States)
Publication Date:
Report Number(s):
BNL-207884-2018-JAAM
Journal ID: ISSN 2469-9950; PRBMDO
Grant/Contract Number:
SC0012704; W911NF-17-1-0399; NSF-DMR-1654041; FG02-99ER45747
Type:
Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 97; Journal Issue: 22; Journal ID: ISSN 2469-9950
Publisher:
American Physical Society (APS)
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); US Army Research Office (ARO); National Science Foundation (NSF)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
OSTI Identifier:
1462410
Alternate Identifier(s):
OSTI ID: 1441022

Zhao, He, Rachmilowitz, Bryan, Ren, Zheng, Han, Ruobin, Schneeloch, J., Zhong, Ruidan, Gu, Genda, Wang, Ziqiang, and Zeljkovic, Ilija. Superconducting proximity effect in a topological insulator using Fe(Te, Se). United States: N. p., Web. doi:10.1103/PhysRevB.97.224504.
Zhao, He, Rachmilowitz, Bryan, Ren, Zheng, Han, Ruobin, Schneeloch, J., Zhong, Ruidan, Gu, Genda, Wang, Ziqiang, & Zeljkovic, Ilija. Superconducting proximity effect in a topological insulator using Fe(Te, Se). United States. doi:10.1103/PhysRevB.97.224504.
Zhao, He, Rachmilowitz, Bryan, Ren, Zheng, Han, Ruobin, Schneeloch, J., Zhong, Ruidan, Gu, Genda, Wang, Ziqiang, and Zeljkovic, Ilija. 2018. "Superconducting proximity effect in a topological insulator using Fe(Te, Se)". United States. doi:10.1103/PhysRevB.97.224504.
@article{osti_1462410,
title = {Superconducting proximity effect in a topological insulator using Fe(Te, Se)},
author = {Zhao, He and Rachmilowitz, Bryan and Ren, Zheng and Han, Ruobin and Schneeloch, J. and Zhong, Ruidan and Gu, Genda and Wang, Ziqiang and Zeljkovic, Ilija},
abstractNote = {Interest in the superconducting proximity effect has recently been reignited by theoretical predictions that it could be used to achieve topological superconductivity. Low- Tc superconductors have predominantly been used in this effort, but small energy scales of ~1 meV have hindered the characterization of the emergent electronic phase, limiting it to extremely low temperatures. In this work, we use molecular beam epitaxy to grow topological insulator Bi 2Te3 in a range of thicknesses on top of a high- Tc superconductor Fe(Te,Se). Using scanning tunneling microscopy and spectroscopy, we detect Δind as high as ~3.5 meV, which is the largest reported gap induced by proximity to an s -wave superconductor to date. We find that Δind decays with Bi2Te3 thickness, but remains finite even after the topological surface states have been formed. Finally, by imaging the scattering and interference of surface state electrons, we provide a microscopic visualization of the fully gapped Bi2Te3 surface state due to Cooper pairing. Lastly, our results establish Fe-based high- Tc superconductors as a promising new platform for realizing high- Tc topological superconductivity.},
doi = {10.1103/PhysRevB.97.224504},
journal = {Physical Review B},
number = 22,
volume = 97,
place = {United States},
year = {2018},
month = {6}
}

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