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تسجيل مستخدم جديدFluctuating magnetism of Co- and Cu-doped NaFeAs
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We report an x-ray emission spectroscopy (XES) study of the local fluctuating magnetic moment ($mu_{bare}$) in $mathrm{NaFe_{1-x}Co_{x}As}$ and $mathrm{NaFe_{1-x}Cu_{x}As}$. In NaFeAs, the reduced height of the As ions induces a local magnetic moment higher than $mathrm{Ba_2As_2}$, despite lower T$_N$ and ordered magnetic moment. As NaFeAs is doped with Co $mu_{bare}$ is slightly reduced, whereas Cu doping leaves it unaffected, indicating a different doping mechanism: based on electron counting for Co whereas impurity scattering dominates in the case of Cu. Finally, we observe an increase of $mu_{bare}$ with temperature in all samples as observed in electron- and hole-doped $mathrm{BaFe_2As_2}$. Since both Co and Cu doping display superconductivity, our findings demonstrate that the formation of Cooper pairs is not connected with the complete loss of fluctuating paramagnetic moments.
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