A Mott insulator continuously connected to iron pnictide superconductors

Abstract

Iron-based superconductivity develops near an antiferromagnetic order and out of a bad metal normal state, which has been interpreted as originating from a proximate Mott transition. Whether an actual Mott insulator can be realized in the phase diagram of the iron pnictides remains an open question. Here we use transport, transmission electron microscopy, X-ray absorption spectroscopy, and neutron scattering to demonstrate that NaFe${}_{1-x}$Cu${}_x$As near $x\approx 0.5$ exhibits real space Fe and Cu ordering, and are antiferromagnetic insulators with the insulating behavior persisting above the Néel temperature, indicative of a Mott insulator. Upon decreasing $x$ from $0.5$, the antiferromagnetic ordered moment continuously decreases, yielding to superconductivity around $x=0.05$. Our discovery of a Mott insulating state in NaFe${}_{1-x}$Cu${}_x$As thus makes it the only known Fe-based material in which superconductivity can be smoothly connected to the Mott insulating state, highlighting the important role of electron correlations in the high-$T_{\mathrm{c}}$ superconductivity.

in press, Nat. Commun., 4 figures, supplementary information available upon request

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Cited by in corpus (32)

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• Orbital-selective Mott phase in multiorbital models for iron pnictides and chalcogenides
• Orbital selectivity in electron correlations and superconducting pairing of iron-based superconductors
• Disorder induced power-law gaps in an insulator-metal Mott transition
• Coexistence of ferromagnetic and stripe antiferromagnetic spin fluctuations in SrCo${}_2$As${}_2$
• NaFe${}_{0.56}$Cu${}_{0.44}$As: A pnictide insulating phase induced by on-site Coulomb interaction
• Description of resonant inelastic x-ray scattering in correlated metals
• Intertwined magnetic and nematic orders in semiconducting KFe${}_{0.8}$Ag${}_{1.2}$Te${}_2$
• Mechanism of magnetic phase transition in correlated magnetic metal: insight into itinerant ferromagnet Fe${}_{3-\delta }$GeTe${}_2$
• Pseudogap and weak multifractality in disordered Mott charge-density-wave insulator
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• Orbital-selective coherence-incoherence crossover and metal-insulator transition in Cu-doped NaFeAs
• Spin-isotropic continuum of spin excitations in antiferromagnetically ordered Fe${}_{1.07}$Te
• Anisotropic magnetic excitations of a frustrated bilinear-biquadratic spin model -- Implications for spin waves of detwinned iron pnictides
• Stripe Antiferromagnetism and Disorder in the Mott Insulator NaFe${}_{1-x}$Cu${}_x$As ($x\lesssim 0.5$)
• Putative hybridization gap in CaMn${}_2$Bi${}_2$ under applied pressure
• Toward the Mott state with Magnetic Cluster Formation in Heavily Cu-Doped NaFe${}_{1-x}$Cu${}_x$As
• Nematic fluctuations in the non-superconducting iron pnictide BaFe${}_{1.9-x}$Ni${}_{0.1}$Cr${}_x$As${}_2$
• Cu doping effects on the electronic structure of Fe1-xCuxSe
• Electronic and spin dynamics in the insulating iron pnictide NaFe${}_{0.5}$Cu${}_{0.5}$As
• RKKY coupled local moment magnetism in NaFe${}_{1-x}$Cu${}_x$As
• Stabilization of antiferromagnetism in 1T-Fe${}_{0.05}$TaS${}_2$
• Spin dynamics in NaFeAs and NaFe${}_{0.53}$Cu${}_{0.47}$As probed by resonant inelastic X-ray scattering
• Enhanced low-energy magnetic excitations evidencing the Cu-induced localization in an Fe-based superconductor Fe${}_{0.98}$Te${}_{0.5}$Se${}_{0.5}$
• Crystalline anisotropy induces a second antiferromagnetic phase in the absence of SDW in the heavily hydrogen-doped LaFeAsO${}_{1-x}$H${}_x$ $(x\sim 0.5)$
• Fluctuating magnetism of Co- and Cu-doped NaFeAs
• Raman scattering study of NaFe${}_{0.53}$Cu${}_{0.47}$As
• Twinning of domains and spin anisotropy in K${}_5$Fe${}_4$Ag${}_6$Te${}_{10}$
• Strong local moment antiferromagnetic spin fluctuations in V-doped LiFeAs
• Quasi-one-dimensional spin excitations in the iron pnictide NaFe${}_{0.53}$Cu${}_{0.47}$As