Depth-resolved magnetic and structural analysis of relaxing epitaxialSr2CrReO6

Abstract

Structural relaxation in a ${\mathrm{Sr}}_{2}{\mathrm{CrReO}}_{6}$ epitaxial film, which exhibits strong spin-orbit coupling, leads to depth-dependent magnetism. We combine two depth-resolved synchrotron x-ray techniques---two-dimensional reciprocal space mapping and x-ray magnetic circular dichroism---to quantitatively determine this effect. An 800-nm-thick film of ${\mathrm{Sr}}_{2}{\mathrm{CrReO}}_{6}$, grown with tensile epitaxial strain on ${\mathrm{SrCr}}_{0.5}{\mathrm{Nb}}_{0.5}{\mathrm{O}}_{3}(225\phantom{\rule{0.16em}{0ex}}\mathrm{nm})/{\text{(LaAlO}}_{3}{)}_{0.3}({\text{Sr}}_{2}{\mathrm{AlTaO}}_{6}{)}_{0.7}$, relaxes away from the ${\mathrm{Sr}}_{2}{\mathrm{CrReO}}_{6}{\text{/SrCr}}_{0.5}{\mathrm{Nb}}_{0.5}{\mathrm{O}}_{3}$ interface to its bulk lattice parameters, with much of the film being fully relaxed. Grazing incidence x-ray diffraction of the film elucidates the in-plane strain relaxation near the film-substrate interface, while depth-resolved x-ray magnetic circular dichroism at the Re L edge reveals the magnetic contributions of the Re site. The smooth relaxation of the film near the interface correlates with changes in the magnetic anisotropy. This provides a systematic and powerful way to probe the depth-varying structural and magnetic properties of a complex oxide with synchrotron-source x-ray techniques.