Intra-layer doping effects on the high-energy magnetic correlations in NaFeAs

TL;DR

This study investigates how intra-layer Co doping affects high-energy magnetic excitations in NaFeAs using RIXS and susceptibility calculations, revealing robustness of magnetic modes against doping and differences based on dopant location.

Contribution

It provides new insights into the doping effects on magnetic excitations in NaFeAs, highlighting the persistence of magnetic modes and the influence of dopant position within the lattice.

Findings

Magnetic excitations persist across doping levels.

Magnetic bandwidths are unaffected by doping.

Doping reduces magnetic spectral weight, especially when dopants are inside the Fe-As layer.

Abstract

We have used Resonant Inelastic X-ray Scattering (RIXS) and dynamical susceptibility calculations to study the magnetic excitations in NaFe$_{1-x}$Co$_x$As (x = 0, 0.03, and 0.08). Despite a relatively low ordered magnetic moment, collective magnetic modes are observed in parent compounds (x = 0) and persist in optimally (x = 0.03) and overdoped (x = 0.08) samples. Their magnetic bandwidths are unaffected by doping within the range investigated. High energy magnetic excitations in iron pnictides are robust against doping, and present irrespectively of the ordered magnetic moment. Nevertheless, Co doping slightly reduces the overall magnetic spectral weight, differently from previous studies on hole-doped BaFe$_{2}$As$_{2}$, where it was observed constant. Finally, we demonstrate that the doping evolution of magnetic modes is different for the dopants being inside or outside the Fe-As layer.