Simultaneous emergence of superconductivity, inter-pocket scattering and nematic fluctuation in potassium-coated FeSe superconductor

Abstract

Superconductivity originates from pairing of electrons. Pairing channel on Fermi surface and pairing glue are thus two pivotal issues for understanding a superconductor. Recently, high-temperature superconductivity over 40 K was found in electron-doped FeSe superconductors including K${}_x$Fe${}_{2-y}$Se${}_2$, Li${}_{0.8}$Fe${}_{0.2}$OHFeSe, and 1 monolayer FeSe thin film. However, their pairing mechanism remains controversial. Here, we studied the systematic evolution of electronic structure in potassium-coated FeSe single crystal. The doping level is controlled precisely by in situ evaporating potassium onto the sample surface. We found that the superconductivity emerges when the inter-pocket scattering between two electron pockets is turned on by a Lifshitz transition of Fermi surface. The nematic order suppresses remarkably at the same doping and strong nematic fluctuation remains in a wide doping range of the phase diagram. Our results suggest an underlying correlation among superconductivity, inter-pocket scattering, and nematic fluctuation in electron-doped FeSe superconductors.

arXiv comment19 pages, 4 figures

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Cited by in corpus (19)

• Role of the orbital degree of freedom in iron-based superconductors
• Monolayer FeSe on SrTiO${}_3$
• Universal Substrate Effect on the Superconductivity of FeSe Monolayer Films
• The Role of SrTiO3 Phonon Penetrating into thin FeSe Films in the Enhancement of Superconductivity
• Evolution of the Fermi surface of the nematic superconductors FeSe1-xSx
• Effect of nematic ordering on electronic structure of FeSe
• Ubiquitous strong electron phonon coupling at the interface of FeSe/SrTiO3
• High-temperature superconductivity in one-unit-cell FeSe films
• Superconductivity in FeSe thin films driven by the interplay between nematic fluctuations and spin-orbit coupling
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• Collapse of critical nematic fluctuations in FeSe under pressure
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• Energy scale of nematic ordering in the parent iron-based superconductor:BaFe2As2
• The study of intrinsic defect state of FeSe with scanning tunneling microscopy
• Insulating Parent Phase and Distinct Doping Evolution to Superconductivity in Single-Layer FeSe/SrTiO3 Films
• Isotropic Cooper Pairs with Emergent Sign Changes in Single-Layer Iron Superconductor
• Effect of the sample work function on alkali metal dosing induced electronic structure change