Direct imaging of electron transfer and its influence on superconducting pairing at FeSe/SrTiO
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eaao2682.full.pdf
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Author(s)
Zhao, Weiwei
Jiang, Jue
Wu, Lijun
Liu, Chaoxing
Zhu, Yimei
Chan, Moses H. W.
Li, Mingda
Chang, Cui-zu
Moodera, Jagadeesh
Date Issued
March 2018
Journal
Science Advances
Publisher
American Association for the Advancement of Science (AAAS)
Citation
Zhao, Weiwei, Mingda Li, Cui-Zu Chang, Jue Jiang, Lijun Wu, Chaoxing Liu, Jagadeesh S. Moodera, Yimei Zhu, and Moses H. W. Chan. “Direct Imaging of Electron Transfer and Its Influence on Superconducting Pairing at FeSe/SrTiO3interface.” Science Advances 4, no. 3 (March 2018): eaao2682.
Version
Final published version
Abstract
The exact mechanism responsible for the significant enhancement of the superconducting transition temperature (Tc) of monolayer iron selenide (FeSe) films on SrTiO₃(STO) over that of bulk FeSe is an open issue. We present the results of a coordinated study of electrical transport, low temperature electron energy-loss spectroscopy (EELS), and high-Angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) measurements on FeSe/STO films of different thicknesses. HAADF-STEM imaging together with EELS mapping across the FeSe/STO interface shows direct evidence of electrons transferred from STO to the FeSe layer. The transferred electrons were found to accumulate within the first two atomic layers of the FeSe films near the STO substrate. An additional Se layer is also resolved to reside between the FeSe film and the TiOx-terminated STO substrate. Our transport results found that a positive backgate applied from STO is particularly effective in enhancing Tcof the films while minimally changing the carrier density. This increase in Tcis due to the positive backgate that "pulls" the transferred electrons in FeSe films closer to the interface and thus enhances their coupling to interfacial phonons and also the electron-electron interaction within FeSe films.
MIT Department
Massachusetts Institute of Technology. Department of Mechanical Engineering
Massachusetts Institute of Technology. Department of Nuclear Science and Engineering
Massachusetts Institute of Technology. Department of Physics
Massachusetts Institute of Technology. Plasma Science and Fusion Center
MIT Energy Initiative
Francis Bitter Magnet Laboratory (Massachusetts Institute of Technology)
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Creative Commons Attribution-NonCommercial 4.0 International
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DOI of Published Version
https://doi.org/10.1126/SCIADV.AAO2682
