Local and collective magnetism ofEuFe2As2

We present an experimental study of the local and collective magnetism of ${\mathrm{EuFe}}_{2}{\mathrm{As}}_{2}$ that is isostructural with the high-temperature superconductor parent compound ${\mathrm{BaFe}}_{2}{\mathrm{As}}_{2}$. In contrast to ${\mathrm{BaFe}}_{2}{\mathrm{As}}_{2}$, where only Fe spins order, ${\mathrm{EuFe}}_{2}{\mathrm{As}}_{2}$ has an additional magnetic transition below 20 K due to the ordering of the ${\mathrm{Eu}}^{2+}$ spins $(J=7/2$, with $L=0$ and $S=7/2)$ in an $A$-type antiferromagnetic texture (ferromagnetic layers stacked antiferromagnetically). This may potentially affect the FeAs layer and its local and correlated magnetism. $\mathrm{Fe}\phantom{\rule{0.16em}{0ex}}K\ensuremath{\beta}$ x-ray emission experiments on ${\mathrm{EuFe}}_{2}{\mathrm{As}}_{2}$ single crystals reveal a local magnetic moment of $1.3\ifmmode\pm\else\textpm\fi{}0.15{\ensuremath{\mu}}_{B}$ at 15 K that increases slightly to $1.45\ifmmode\pm\else\textpm\fi{}0.15{\ensuremath{\mu}}_{B}$ at 300 K. Resonant inelastic x-ray scattering experiments performed on the same crystals show dispersive broad (in energy) magnetic excitations along $(0,0)\ensuremath{\rightarrow}(1,0)$ and $(0,0)\ensuremath{\rightarrow}(1,1)$ with a bandwidth on the order of 170--180 meV. These results on local and collective magnetism are in line with other parent compounds of the ${\mathrm{AFe}}_{2}{\mathrm{As}}_{2}$ series $(A=\mathrm{Ba}$, Ca, and Sr), especially the well-characterized ${\mathrm{BaFe}}_{2}{\mathrm{As}}_{2}$. Thus, our experiments lead us to the conclusion that the effect of the high magnetic moment of Eu on the magnitude of both the Fe local magnetic moment and spin excitations is small and confined to low-energy excitations.