Effects of strain and buffer layer on interfacial magnetization in ${\mathrm{Sr}}_2{\mathrm{CrReO}}_6$ films determined by polarized neutron reflectometry

We have determined the depth-resolved magnetization structures of a series of highly ordered ${\mathrm{Sr}}_2{\mathrm{CrReO}}_6$ (SCRO) ferrimagnetic epitaxial films via combined studies of x-ray reflectometry, polarized neutron reflectometry, and superconducting quantum interference device magnetometry. The SCRO films deposited directly on ${\left({\mathrm{LaAlO}}_3\right)}_{0.3}{\left({\mathrm{Sr}}_2{\mathrm{AlTaO}}_6\right)}_{0.7}$ or ${\mathrm{SrTiO}}_3$ substrates show reduced magnetization of similar width near the interfaces with the substrates, despite having different degrees of strain. When the SCRO film is deposited on a ${\mathrm{SrCr}}_{0.5}{\mathrm{Nb}}_{0.5}{\mathrm{O}}_3$ (SCNO) double perovskite buffer layer, the width of the interfacial region with reduced magnetization is decreased. However, the relative reduction of the magnetization averaged over the interfacial regions is comparable among the three samples. Interestingly, we found that the magnetization suppression region is wider than the Cr/Re antisite disorder region at the interface between SCRO and SCNO.

Figure 1

Magnetic hysteresis loops from the three SCRO films grown on (a) LSAT, (b) STO, and (c) a SCNO buffer layer, respectively. Data were collected between $+70$ and $-70$ kOe at 300 K, and have been normalized by the area of the films. PNR experiments were performed at 11.5 kOe, as indicated by the dashed lines.

Figure 2

Results on the 20 nm SCRO film on LSAT. (a) X-ray reflectivity and (b) polarized neutron reflectivity at 300 K and 120 K in a 11.5 kOe in-plane magnetic field. The best fit curves (lines) are overlaid on the top of the data (circles). (c) The depth profiles of the real parts of the x-ray and nuclear scattering length densities (SLDs, top) and the magnetization ($M$, bottom).

Figure 3

Results on the 20 nm SCRO film on STO. (a) X-ray reflectivity and (b) polarized neutron reflectivity at 300 K and 120 K in a 11.5 kOe in-plane magnetic field. (c) The depth profiles of the real parts of the x-ray and nuclear scattering length densities (top) and the magnetization (bottom).

Figure 4

Results on the 20 nm SCRO film on a 50-nm SCNO buffer layer on STO. (a) X-ray reflectivity and (b) polarized neutron reflectivity at 300 K and 120 K in a 11.5 kOe in-plane magnetic field. (c) The depth profiles of the real parts of the x-ray and nuclear scattering length densities (top) and the magnetization (bottom).