Depth-resolved magnetic and structural analysis of relaxing epitaxial Sr$_2$CrReO$_6$*

Structural relaxation in a Sr$_2$CrReO$_6$ epitaxial film, with strong spin-orbit coupling, leads to depth-dependent magnetism. We combine a couple of depth-resolved synchrotron x-ray techniques, including two-dimensional reciprocal space mapping and x-ray magnetic circular dichroism experiments, to demonstrate this effect. An 800 nm film of Sr$_2$CrReO$_6$, grown with tensile epitaxial strain on SrCr$_{0.5}$Nb$_{0.5}$O$_3$(200 nm)/LSAT, relaxes away from the Sr$_2$CrReO$_6$/SrCr$_{0.5}$Nb$_{0.5}$O$_3$ interface. Grazing incidence x-ray diffraction measurements of the film elucidate the in-plane strain relaxation while depth-resolved x-ray magnetic circular dichroism at the Re \textit{L} edge reveals the magnetic contributions of the Re site. The smooth relaxation of the film correlates with a systematic change in the magnetism.This provides an interesting and powerful way to probe the depth-varying structural and magnetic properties of a complex oxide with synchrotron-source x-ray techniques.