Experimental Demonstration of the Sign Reversal of the Order Parameter in (Li1-xFex)OHFe1-yZnySe

Abstract

Iron pnictides are the only known family of unconventional high-temperature superconductors besides cuprates. Until recently, it was widely accepted that superconductivity is spin-fluctuation driven and intimately related to their fermiology, specifically, hole and electron pockets separated by the same wave vector that characterizes the dominant spin fluctuations, and supporting order parameters (OP) of opposite signs. This picture was questioned after the discovery of a new family, based on the FeSe layers, either intercalated or in the monolayer form. The critical temperatures there reach ~40 K, the same as in optimally doped bulk FeSe - despite the fact that intercalation removes the hole pockets from the Fermi level and, seemingly, undermines the basis for the spin-fluctuation theory and the idea of a sign-changing OP. In this paper, using the recently proposed phase-sensitive quasiparticle interference technique, we show that in LiOH intercalated FeSe compound the OP does change sign, albeit within the electronic pockets, and not between the hole and electron ones. This result unifies the pairing mechanism of iron based superconductors with or without the hole Fermi pockets and supports the conclusion that spin fluctuations play the key role in electron pairing.

29 pages, 6 figures, including Supplementary Information

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• Unconventional pairing originating from disconnected Fermi surfaces in superconducting LaFeAsO${}_{1-x}$F${}_x$}
• Fe-based high temperature superconductivity with Tc=31K bordering an insulating antiferromagnet in (Tl,K)FexSe2 Crystals
• Structure determination and coexistence of superconductivity and antiferromagnetic order in (Li0.8Fe0.2)OHFeSe
• Self-Consistent Vertex Correction Analysis for Iron-Based Superconductors: Mechanism of Coulomb-Interaction-Driven Orbital Fluctuations
• d-wave pairing from spin fluctuations in the KxFe{2-y}Se2 superconductors
• Monolayer FeSe on SrTiO${}_3$
• Superfluid density of the $\pm$s-wave state for the iron-based superconductors
• Coexistence of 3d-ferromagnetism and superconductivity in [(Li(1-x)Fex)OH](Fe(1-y)Liy)Se
• Inter-pocket pairing and gap symmetry in Fe-based superconductors with only electron pockets
• Angle-resolved photoemission evidence of s-wave superconducting gap in KxFe2-ySe2 superconductor
• Single Impurity Problem in Iron-Pnictide Superconductors
• Spin resonance in the superconducting state of Li${}_{1-x}$Fe${}_x$ODFe${}_{1-y}$Se observed by neutron spectroscopy

Cited by in corpus (44)

• Electronic structure of quantum materials studied by angle-resolved photoemission spectroscopy
• Two superconducting components with different symmetries in Nd1-xSrxNiO2 films
• On the Remarkable Superconductivity of FeSe and its Close Cousins
• Superconductivity in nickel based 112 systems
• Exploring Topological Superconductivity in Topological Materials
• Sensitive dependence of pairing symmetry on Ni-$e_g$ crystal field splitting in the nickelate superconductor La${}_3$Ni${}_2$O${}_7$
• Odd and even modes of neutron spin resonance in the bilayer iron-based superconductor CaKFe${}_4$As${}_4$
• Directly visualizing the sign change of d-wave superconducting gap in Bi2Sr2CaCu2O8+δ by phase-referenced quasiparticle interference
• Topological Superconductivity in an s-wave Superconductor and Its Implication to Iron-based Superconductors
• Unconventional density waves and superconductivities in Fe-based superconductors and other strongly correlated electron systems
• Detection of bosonic mode as a signature of magnetic excitation in one unit cell FeSe on SrTiO3
• Single particle tunneling spectroscopy and superconducting gaps in layered iron based superconductor KCa${}_2$Fe${}_4$As${}_4$F${}_2$
• Classification of Symmetry Derived Pairing at M Point in FeSe
• Heterostructural one-unit-cell FeSe/SrTiO3: from high-temperature superconductivity to topological states
• An extensive impurity-scattering study on the pairing symmetry of monolayer FeSe films on SrTiO3
• Direct visualization of sign reversal s^+- superconducting gaps in FeTe0.55Se0.45
• Visualization of local magnetic moments emerging from impurities in the Hund's metal states of FeSe
• Raman Study of Cooper Pairing Instabilities in (Li${}_{1-x}$Fe${}_x$)OHFeSe
• Realization of continuously electron doping in bulk iron selenides and identification of a new superconducting zone
• Sign reversal superconducting gaps revealed by phase referenced quasi-particle interference of impurity induced bound states in (Li${}_{1-x}$Fe${}_x$)OHFe${}_{1-y}$Zn${}_y$Se
• Detecting sign-changing superconducting gap in LiFeAs using quasiparticle interference
• The study of intrinsic defect state of FeSe with scanning tunneling microscopy
• Phase-sensitive determination of nodal $\mathbf{d}$-wave order parameter in single-band and multiband superconductors
• Quasiparticle interference as a direct experimental probe of bulk odd-frequency superconducting pairing
• Possible pairing symmetry in the FeSe-based superconductors determined by quasiparticle interference
• Quasiparticle Interference and Symmetry of Superconducting Order Parameter in Strongly Electron-Doped Iron-based Superconductors
• Quasi-one Dimensional Nanostructures as Sign of Nematicity in Iron Pnictides and Chalcogenides
• Orbital-Selective High-Temperature Cooper Pairing Developed in the Two-Dimensional Limit
• Dispersionless orbital excitations in (Li,Fe)OHFeSe superconductors
• Multi-Atom Quasiparticle Scattering Interference for Superconductor Energy-Gap Symmetry Determination
• Many-body physics-induced selection rules: application to Raman spectroscopy
• Anisotropic gap structure and sign reversal symmetry in monolayer Fe(Se,Te)
• Long range magnetic order in hydroxide layer doped (Li${}_{1-x-y}$Fe${}_x$Mn${}_y$OD)FeSe
• Lateral quantum confinement effect on monolayer high-Tc superconductors
• The Future of the Correlated Electron Problem
• Effect of the additional Se layer on the electronic structure of iron-based superconductor FeSe/SrTiO${}_3$
• Crystal structures and the sign reversal Hall resistivity in iron-based superconductors Lix(C3H10N2)0.32FeSe (0.15<x<0.4)
• Field-induced coexistence of $s_{++}$ and $s_{\pm }$ superconducting states in dirty multiband superconductors
• Revealing sign-reversal $s^{+-}$-wave pairing by quasiparticle interference in the heavy-fermion superconductor CeCu${}_2$Si${}_2$
• Anisotropic response of defect bound states to magnetic field in epitaxial FeSn films
• Nodeless multigap superconductivity in organic-ion-intercalated (tetrabutyl~ammonium)${}_{0.3}$FeSe
• Band structure of organic-ion-intercalated (EMIM)${}_x$FeSe superconductor
• Hot-lines topology and the fate of the spin resonance mode in three-dimensional unconventional superconductors
• Quasiparticle Interference of Spin-Triplet Superconductors: Application to UTe${}_2$