Abstract
We use transport and neutron scattering to study the electronic phase diagram and spin excitations of NaFe1-xCuxAs single crystals. Similar to Co- and Ni-doped NaFeAs, a bulk superconducting phase appears near x≈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≈50%. Using transport measurements, we demonstrate that the resistivity in NaFe1-xCuxAs exhibits non-Fermi-liquid behavior near x≈1.8%. 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 NaFe1-xCuxAs is continuously connected to an antiferromagnetically ordered insulating phase near x≈50% with significant electronic correlations. Therefore, electron correlations is an important ingredient of superconductivity in NaFe1-xCuxAs and other iron pnictides.
| Original language | English |
|---|---|
| Article number | 054501 |
| Journal | Physical Review B |
| Volume | 95 |
| Issue number | 5 |
| DOIs | |
| State | Published - Feb 3 2017 |
Funding
The single crystal growth and neutron scattering work at Rice is supported by the U.S. DOE, BES under Contract No. DE-SC0012311 (P.D.). A part of the material synthesis work at Rice is supported by the Robert A. Welch Foundation Grant No. C-1839 (P.D.). Research at BNU and IOP are supported by the National Basic Research Program of China (973 Program, Grant No. 2012CB821401), National Natural Science Foundation of China (Grant No. 11374011), and the Fundamental Research Funds for the Central Universities (Grant No. 2014KJJCB27). A portion of this research used resources at the High Flux Isotope Reactor and Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory.