Temperature-induced orbital selective localization and coherent-incoherent crossover in single-layer FeSe/Nb:BaTiO3/KTaO3

Y. J. Pu, Z. C. Huang, H. C. Xu, D. F. Xu, Q. Song, C. H. P. Wen, R. Peng, and D. L. Feng
Phys. Rev. B 94, 115146 – Published 21 September 2016

Abstract

Iron chalcogenide superconductors are multiorbital materials with strong electron correlations. Here we use angle-resolved photoemission spectroscopy to study orbital dependent correlation effects in single-layer FeSe/Nb:BaTiO3/KTaO3, an iron chalcogenide superconductor with high interfacial superconductivity, nondegenerate electron pockets, and varied electron correlation compared with single-layer FeSe/SrTiO3. Signatures of polaronic behavior are observed over the whole temperature range, suggesting electron-boson interactions. Moreover, the nondegeneracy of the electron bands helps to resolve the temperature dependent evolution of different bands. The coherent spectral weight of one electron band significantly decreases above 115 K and is completely depleted at 200 K while that of the other one remains finite, giving direct evidence of an orbital selective Mott crossover. Correspondingly, the weight of the incoherent photoemission spectra is enhanced, indicating a coherent-incoherent crossover during the Mott crossover process. Compared with that in single-layer FeSe/SrTiO3, the depletion temperature of the dxy band is higher in single-layer FeSe/Nb:BaTiO3/KTaO3 due to the decreased correlation of the dxy band in FeSe/Nb:BaTiO3. These phenomena help to construct a more complete picture of electron correlations in the FeSe family.

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  • Received 21 April 2016
  • Revised 16 August 2016

DOI:https://doi.org/10.1103/PhysRevB.94.115146

©2016 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Y. J. Pu, Z. C. Huang, H. C. Xu, D. F. Xu, Q. Song, C. H. P. Wen, R. Peng*, and D. L. Feng

  • State Key Laboratory of Surface Physics, Department of Physics, and Laboratory of Advanced Materials, Fudan University, Shanghai 200433, China and Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China

  • *pengrui@fudan.edu.cn
  • dlfeng@fudan.edu.cn

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Vol. 94, Iss. 11 — 15 September 2016

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