2 research outputs found
Phase diagram and neutron spin resonance of superconducting NaFe1âxCuxAs
We use transport and neutron scattering to study the electronic phase diagram and spin excitations of NaFe1âxCuxAs single crystals. Similar to Co- and Ni-doped NaFeAs, a bulk superconducting phase appears near xâ2% 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 xâ50%. Using transport measurements, we demonstrate that the resistivity in NaFe1âxCuxAs exhibits non-Fermi-liquid behavior near xâ1.8%. Our inelastic neutron scattering experiments reveal a single neutron spin resonance mode exhibiting weak dispersion along c axis in NaFe0.98Cu0.02As. The resonance is high in energy relative to the superconducting transition temperature Tc but weak in intensity, likely resulting from impurity effects. These results are similar to other iron pnictides superconductors despite that the superconducting phase in NaFe1âxCuxAs is continuously connected to an antiferromagnetically ordered insulating phase near xâ50% with significant electronic correlations. Therefore, electron correlations is an important ingredient of superconductivity in NaFe1âxCuxAs and other iron pnictides