Spectroscopic Imaging of Quasiparticle Bound States Induced by Strong Nonmagnetic Scatterings in One-Unit-Cell FeSe/SrTiO3

Chaofei Liu, Ziqiao Wang, Yi Gao, Xiaoqiang Liu, Yi Liu, Qiang-Hua Wang, and Jian Wang
Phys. Rev. Lett. 123, 036801 – Published 15 July 2019
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Abstract

The absence of holelike Fermi pockets in the heavily electron-doped iron selenides (HEDISs) challenges the s±-wave pairing originally proposed for iron pnictides, which consists of opposite signs of the gap function on electron and hole pockets. While the HEDIS compounds have been investigated extensively, a consistent description of the superconducting pairing therein is still lacking. Here, by in situ scanning tunneling spectroscopy and theoretical calculations, we study the effects of strong scatterings from nonmagnetic Pb adatoms on the epitaxially grown HEDIS, one-unit-cell FeSe/SrTiO3(001). Systematic tunneling spectra measured on the Pb adatoms show comprehensive signals of quasiparticle bound states, which can be well explained theoretically within the sign-reversing pairing scenarios. The finding implies that, in addition to previously detected phonons, spin fluctuations play an important role in driving the Cooper pairing in FeSe/SrTiO3(001). The sign reversal in the gap function we revealed here is a significant ingredient in a unified understanding of the high-temperature superconductivity in HEDISs.

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  • Received 24 February 2019

DOI:https://doi.org/10.1103/PhysRevLett.123.036801

© 2019 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Chaofei Liu1, Ziqiao Wang1, Yi Gao2, Xiaoqiang Liu1, Yi Liu1, Qiang-Hua Wang3,4,*, and Jian Wang1,5,6,7,†

  • 1International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
  • 2Center for Quantum Transport and Thermal Energy Science, Jiangsu Key Lab on Opto-Electronic Technology, School of Physics and Technology, Nanjing Normal University, Nanjing 210023, China
  • 3National Laboratory of Solid State Microstructures and School of Physics, Nanjing University, Nanjing 210093, China
  • 4Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
  • 5Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
  • 6CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China
  • 7Beijing Academy of Quantum Information Sciences, Beijing 100193, China

  • *Corresponding author. qhwang@nju.edu.cn
  • Corresponding author. jianwangphysics@pku.edu.cn

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Issue

Vol. 123, Iss. 3 — 19 July 2019

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