Phase diagram and neutron spin resonance of superconducting NaFe${}_{1-x}$Cu${}_x$As

Abstract

We use transport and neutron scattering to study the electronic phase diagram and spin excitations of NaFe${}_{1-x}$Cu${}_x$As single crystals. Similar to Co- and Ni-doped NaFeAs, a bulk superconducting phase appears near $x\approx 2\%$ with the suppression of stripe-type magnetic order in NaFeAs. Upon further increasing Cu concentration the system becomes insulating, culminating in an antiferromagnetically ordered insulating phase near $x\approx 50\%$. Using transport measurements, we demonstrate that the resistivity in NaFe${}_{1-x}$Cu${}_x$As exhibits non-Fermi-liquid behavior near $x\approx 1.8\%$. Our inelastic neutron scattering experiments reveal a single neutron spin resonance mode exhibiting weak dispersion along $c$-axis in NaFe${}_{0.98}$Cu${}_{0.02}$As. The resonance is high in energy relative to the superconducting transition temperature $T_{\mathrm{c}}$ but weak in intensity, likely resulting from impurity effects. These results are similar to other iron pnictides superconductors despite the superconducting phase in NaFe${}_{1-x}$Cu${}_x$As is continuously connected to an antiferromagnetically ordered insulating phase near $x\approx 50\%$ with significant electronic correlations. Therefore, electron correlations is an important ingredient of superconductivity in NaFe${}_{1-x}$Cu${}_x$As and other iron pnictides.

accepted for publication in PRB

References in corpus (12)

• Strong Correlations and Magnetic Frustration in the High Tc Iron Pnictides
• Three-dimensional Resonance in superconducting BaFe${}_{1.9}$Ni${}_{0.1}$As${}_2$
• Incommensurate spin-density wave order in electron-doped BaFe2As2 superconductors
• Crossover from weak to strong pairing in unconventional superconductors
• Coexistence and competition of the short-range incommensurate antiferromagnetic order with superconductivity in BaFe2-xNixAs2
• Dependence of carrier doping on the impurity potential in transition-metal-substituted FeAs-based superconductors
• Electronic structure of BaCu${}_2$As${}_2$ and SrCu${}_2$As${}_2$: sp-band metals
• Hourglass dispersion and resonance of magnetic excitations in the superconducting state of the single-layer cuprate HgBa2CuO4+δ near optimal doping
• A crossover in phase diagram of NaFe${}_{1-x}$Co${}_x$As determined by electronic transport measurements
• NaFe${}_{0.56}$Cu${}_{0.44}$As: A pnictide insulating phase induced by on-site Coulomb interaction
• Spin anisotropy due to spin-orbit coupling in optimally hole-doped Ba${}_{0.67}$K${}_{0.33}$Fe${}_2$As${}_2$
• Strong similarities between the local electronic structure of insulating iron pnictide and lightly doped cuprate

Cited by in corpus (4)

• Local breaking of four-fold rotational symmetry by short-range magnetic order in heavily overdoped Ba(Fe${}_{1-x}$Cu${}_x$)${}_2$As${}_2$
• Orbital-selective coherence-incoherence crossover and metal-insulator transition in Cu-doped NaFeAs
• RKKY coupled local moment magnetism in NaFe${}_{1-x}$Cu${}_x$As
• Fluctuating magnetism of Co- and Cu-doped NaFeAs