Effects of Strain and Buffer Layer on Interfacial Magnetization in Sr$_2$CrReO$_6$ Films*

Magnetic double-perovskite Sr$_2$CrReO$_6$ (SCRO) has several functional properties including a T$_C >$ 500 K, high spin polarization, large spin-orbit interaction, and semiconducting behavior in highly ordered films. However, fabrication of highly ordered films is still challenging, and progress toward device applications requires an in-depth understanding of the electronic and magnetic properties, especially at interfaces. We have investigated how the Cr/Re antisite disorder and strain affect the interfacial magnetization in SCRO films via x-ray and polarized neutron reflectometry [1]. We find that the magnetization of SCRO films is reduced near the interface with the substrate. The width of this interfacial layer weakly depends on the strain and decreases when a SrCr$_{0.5}$Nb$_{0.5}$O$_3$ (SCNO) buffer layer is used to reduce the antisite disorder. Interestingly, for the SCRO film deposited on a SCNO buffer layer, the region with reduced magnetization is wider than the antisite disorder region at the SCRO/SCNO interface, suggesting that antisite disorder is not the only mechanism reducing the magnetization. [1] Yaohua Liu {\it et al.}, Phys. Rev. B 90, 104416 (2014).