NaFe${}_{0.56}$Cu${}_{0.44}$As: A pnictide insulating phase induced by on-site Coulomb interaction

Abstract

In the studies of iron-pnictides, a key question is whether their bad-metal state from which the superconductivity emerges lies in close proximity with a magnetically ordered insulating phase. Recently it was found that at low temperatures, the heavily Cu-doped NaFe${}_{1-x}$Cu${}_x$As ($x>0.3$) iron-pnictide is an insulator with long-range antiferromagnetic order, similar to the parent compound of cuprates but distinct from all other iron-pnictides. Using angle-resolved photoemission spectroscopy, we determined the momentum-resolved electronic structure of NaFe${}_{1-x}$Cu${}_x$As ($x=0.44$) and identified that its ground state is a narrow-gap insulator. Combining the experimental results with density functional theory (DFT) and DFT+U calculations, our analysis reveals that the on-site Coulombic (Hubbard) and Hund's coupling energies play crucial roles in formation of the band gap about the chemical potential. We propose that at finite temperatures charge carriers are thermally excited from the Cu-As-like valence band into the conduction band, which is of Fe $3d$-like character. With increasing temperature, the number of electrons in the conduction band becomes larger and the hopping energy between Fe sites increases, and finally the long-range antiferromagnetic order is destroyed at $T>T_{\mathrm{N}}$. Our study provides a basis for investigating the evolution of the electronic structure of a Mott insulator transforming into a bad metallic phase, and eventually forming a superconducting state in iron-pnictidesa superconducting state in iron-pnictides.

References in corpus (32)

• Superconductivity in Iron Compounds
• High-temperature superconductivity in iron-based materials
• Strong electronic correlations from Hund's coupling
• Kinetic frustration and the nature of the magnetic and paramagnetic states in iron pnictides and iron chalcogenides
• The pseudogap: friend or foe of high Tc?
• Coherence-incoherence crossover in the normal state of iron-oxypnictides and importance of the Hund's rule coupling
• High Temperature Superconductivity in Iron Pnictides and Chalcogenides
• Selective Mottness as a key to iron superconductors
• Comparison of Ab initio Low-Energy Models for LaFePO, LaFeAsO, BaFe2As2, LiFeAs, FeSe and FeTe: Electron Correlation and Covalency
• Observation of Temperature-Induced Crossover to an Orbital-Selective Mott Phase in A${}_x$Fe${}_{2-y}$Se${}_2$ (A=K, Rb) Superconductors
• Hund's coupling key role in multi-orbital correlations
• Fermi surface of superconducting LaFePO determined by quantum oscillations
• Fe-based superconductors: an angle-resolved photoemission spectroscopy perspective
• Electronic Structure of the BaFe${}_2$As${}_2$ Family of Iron Pnictides
• Impact of the 2 Fe unit cell on the electronic structure measured by ARPES in iron pnictides
• Possible nodal superconducting gap emerging at the Lifshitz transition in heavily hole-doped Ba0.1K0.9Fe2As2
• Multi-Orbital Hubbard Model in Infinite Dimensions: Quantum Monte Carlo Calculation
• Electron scattering, charge order, and pseudogap physics in La${}_{1.6-x}$Nd${}_{0.4}$Sr${}_x$CuO${}_4$: An angle resolved photoemission spectroscopy study
• A Mott insulator continuously connected to iron pnictide superconductors
• Interaction-induced singular Fermi surface in a high-temperature oxypnictide superconductor
• Electronic structure of BaCu${}_2$As${}_2$ and SrCu${}_2$As${}_2$: sp-band metals
• Electronic band structure of BaCo${}_2$As${}_2$: a fully-doped ferropnictide with reduced electronic correlations
• Phase diagram and physical properties of NaFe${}_{1-x}$Cu${}_x$As single crystals
• Spectral properties of transition metal pnictides and chalcogenides: angle-resolved photoemission spectroscopy and dynamical mean field theory
• Bulk electronic structure of superconducting LaRu2P2 single crystals measured by soft x-ray angle-resolved photoemission spectroscopy
• High-temperature superconductivity from fine-tuning of Fermi-surface singularities in iron oxypnictides
• Evolution of normal and superconducting properties of single crystals of Na${}_{1-\delta }$FeAs upon interaction with environment
• Tuning electronic correlations in transition metal pnictides: chemistry beyond the valence count
• Direct spectroscopic evidence for completely filled Cu $3d$ shell in BaCu${}_2$As${}_2$ and $\alpha$-BaCu${}_2$Sb${}_2$
• Strong similarities between the local electronic structure of insulating iron pnictide and lightly doped cuprate
• Localization and Orbital Selectivity in Iron-Based Superconductors with Cu Substitution
• ARPES observation of isotropic superconducting gaps in isovalent Ru-substituted Ba(Fe${}_{0.75}$Ru${}_{0.25}$)${}_2$As${}_2$

Cited by in corpus (14)

• A Mott insulator continuously connected to iron pnictide superconductors
• Description of resonant inelastic x-ray scattering in correlated metals
• Phase diagram and neutron spin resonance of superconducting NaFe${}_{1-x}$Cu${}_x$As
• Orbital-selective coherence-incoherence crossover and metal-insulator transition in Cu-doped NaFeAs
• Stripe Antiferromagnetism and Disorder in the Mott Insulator NaFe${}_{1-x}$Cu${}_x$As ($x\lesssim 0.5$)
• Toward the Mott state with Magnetic Cluster Formation in Heavily Cu-Doped NaFe${}_{1-x}$Cu${}_x$As
• 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
• Spin dynamics in NaFeAs and NaFe${}_{0.53}$Cu${}_{0.47}$As probed by resonant inelastic X-ray scattering
• Fluctuating magnetism of Co- and Cu-doped NaFeAs
• Raman scattering study of NaFe${}_{0.53}$Cu${}_{0.47}$As
• Quasi-one-dimensional spin excitations in the iron pnictide NaFe${}_{0.53}$Cu${}_{0.47}$As
• Strong local moment antiferromagnetic spin fluctuations in V-doped LiFeAs