Optimization of ruthenium as a buffer layer for non-collinear antiferromagnetic Mn3X films

Abstract

Two thin film deposition routes were studied for the growth of high quality single crystalline Ru (0001) epitaxial films on c-Al2O3 substrates using RF-magnetron sputtering. Such films are very important as buffer layers for the deposition of epitaxial non-collinear antiferromagnetic Mn3X films. The first route involved depositing Ru at 700 °C, leading to a smooth 30 nm thick film. Although, high resolution X-ray diffraction (HRXRD) revealed twinned Ru film orientations, the in-situ post-annealing eliminated one orientation, leaving the film orientation aligned with the substrate, with no in-plane lattice rotation and a large lattice mismatch (13.6%). The second route involved deposition of Ru at room temperature followed by in-situ post-annealing at 700 °C. Transmission electron microscopy confirmed a very high quality of these films, free of crystal twinning, and a 30° in-plane lattice rotation relative to the substrate, resulting in a small in-plane lattice mismatch of -1.6%. X-ray reflectivity demonstrated smooth surfaces for films down to 7 nm thickness. 30 nm thick high quality single-crystalline Mn3Ga and Mn3Sn films were grown on top of the Ru buffer deposited using the second route as a first step to realize Mn3X films for antiferromagnetic spintronics applications.

Large Spin Hall Conductivity in Epitaxial Thin Films of Kagome Antiferromagnet Mn3Sn at Room Temperature

“…The location of the peaks indicates that the epitaxial film is formed with a relationship of Mn 3 Sn (0001)[20$$\bar{2}$$0] || Ru (0001)[10$$\bar{1}$$0] || Al 2 O 3 (0001)[11$$\bar{2}$$0], which is similar to the work by S. Kurdi, et al. [ 26 ]…”

“…Similar XRD pattern was recorded in lower thickness of Mn 3 Sn films (see Figure 1e). To determine the epitaxial relationship, we performed 𝜑-scans for the peaks: [11 20], which is similar to the work by S. Kurdi, et al [26] In order to determine the composition and its distribution, we used an electron probe microanalyzer (EPMA) and energy dispersive X-ray (EDX) mapping on our samples. The composition of the film is estimated to be Mn 3.14±0.03 Sn 0.86±0.01 using EDX mapping and Mn 3.12±0.02 Sn 0.88±0.01 by quantitative analysis using EPMA system.…”