Superconducting gap anisotropy in monolayer FeSe thin film

Abstract

Fermi surface topology and pairing symmetry are two pivotal characteristics of a superconductor. Superconductivity in one monolayer (1ML) FeSe thin film has attracted great interest recently due to its intriguing interfacial properties and possibly high superconducting transition temperature (Tc) over 77 K. Here, we report high-resolution measurements of the Fermi surface and superconducting gaps in 1ML FeSe using angle-resolved photoemission spectroscopy (ARPES). Two ellipse-like electron pockets are clearly resolved overlapping with each other at the Brillouin zone corner. The superconducting gap is nodeless but moderately anisotropic, which put strong constraints on determining the pairing symmetry. The gap maxima locate along the major axis of ellipse, which cannot be explained by a single d-wave, extended s-wave, or s$\pm$ gap function. Four gap minima are observed at the intersection of electron pockets suggesting the existence of either a sign change or orbital-dependent pairing in 1ML FeSe.

arXiv comment15 pages, 4 figures

References in corpus (30)

• Unconventional pairing originating from disconnected Fermi surfaces in superconducting LaFeAsO${}_{1-x}$F${}_x$}
• Interface induced high temperature superconductivity in single unit-cell FeSe films on SrTiO3
• Superconductivity in single-layer films of FeSe with a transition temperature above 100 K
• Gap symmetry and structure of Fe-based superconductors
• Phase Diagram and High Temperature Superconductivity at 65 K in Tuning Carrier Concentration of Single-Layer FeSe Films
• Near-degeneracy of several pairing channels in multiorbital models for the Fe-pnictides
• Interfacial mode coupling as the origin of the enhancement of Tc in FeSe films on SrTiO3
• Interface-induced superconductivity and strain-dependent spin density wave in FeSe/SrTiO3 thin films
• Electronic Origin of High Temperature Superconductivity in Single-Layer FeSe Superconductor
• Phenomenology of Photoemission Lineshapes of High Tc Superconductors
• Direct observation of high temperature superconductivity in one-unit-cell FeSe films
• Critical role of substrate in the high temperature superconductivity of single layer FeSe on Nb:BaTiO${}_3$
• Observation of universal strong orbital-dependent correlation effects in iron chalcogenides
• d-wave pairing from spin fluctuations in the KxFe{2-y}Se2 superconductors
• Unconventional Anisotropic s-Wave Superconducting Gaps of LiFeAs Iron-Pnictide Superconductor
• Observation of two distinct $d_{xz}/d_{yz}$ band splittings in FeSe
• Sensitivity of the superconducting state and magnetic susceptibility to key aspects of electronic structure in ferropnictides
• Enhanced superconductivity and evidence for novel pairing in single-layer FeSe on SrTiO3 thin film under large tensile strain
• One-sign order parameter in iron based superconductor
• Symmetry analysis of possible superconducting states in KxFe2Se2 superconductors
• The orbital characters of bands in iron-based superconductor BaFe1.85Co0.15As2
• Large electron-phonon interactions from FeSe phonons in a monolayer
• Impact of the 2 Fe unit cell on the electronic structure measured by ARPES in iron pnictides
• Emergence of Fully-Gapped $s_{++}$-wave and Nodal d-wave States Mediated by Orbital- and Spin-Fluctuations in Ten-Orbital Model for KFe${}_2$Se${}_2$
• Effects of charge doping and constrained magnetization on the electronic structure of an FeSe monolayer
• One-Fe versus Two-Fe Brillouin Zone of Fe-Based Superconductors: Creation of the Electron Pockets via Translational Symmetry Breaking
• Fermiology, Orbital Order, Orbital Fluctuation and Cooper Pairing in Iron-based Superconductors
• Strong pairing at iron $3d_{xz,yz}$ orbitals in hole-doped BaFe${}_2$As${}_2$
• Odd parity pairing and nodeless anti-phase $s^{\pm }$ in Iron-Based Superconductors
• Orbital-Parity Distinct Superconducting Pairing Structures of Fe-based Superconductors under Glide Symmetry

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