Spin polarization of Ru in superconducting Ba(Fe$_{0.795}$Ru$_{0.205}$)$_2$As$_2$ studied by x-ray resonant magnetic scattering

TL;DR

This study uses x-ray resonant magnetic scattering to demonstrate that Ru in the superconducting Ba(Fe$_{0.795}$Ru$_{0.205}$)$_2$As$_2$ is spin-polarized and exhibits magnetic ordering aligned with Fe, revealing magnetic interactions in this compound.

Contribution

First direct evidence of Ru spin polarization in Ba(Fe$_{1-x}$Ru$_x$)$_2$As$_2$ using XRMS at the Ru L2 edge, linking Ru magnetic behavior to Fe magnetic order.

Findings

Resonance enhancements observed at Ru L2 edge

Ru magnetic ordering follows Fe with long correlation length

Ru is confirmed to be spin-polarized in the compound

Abstract

We have employed the x-ray resonant magnetic scattering (XRMS) technique at the Ru $L_2$ edge of the Ba(Fe$_{1-x}$Ru$_x$)$_2$As$_2$ ($x = 0.205$) superconductor. We show that pronounced resonance enhancements at the Ru $L_2$ edge are observed at the wave vector which is consistent with the antiferromagnetic propagation vector of the Fe in the undoped BaFe$_2$As$_2$. We also demonstrate that the XRMS signals at the Ru $L_2$ edge follow the magnetic ordering of the Fe with a long correlation length, $\xi_{ab} > 2850\pm400$ \AA . Our experimental observation shows that the Ru is spin-polarized in Ba(Fe$_{1-x}$Ru$_x$)$_2$As$_2$ compounds.