Title : Seed Ru-assisted epitaxial growth of Mn3Sn thin films: Strain-controlled pathway to piezo-magnetism
Abstract:
Non-collinear anti-ferromagnetic (AFM) materials are the prime candidates for AFM spintronics1. In this regard, growing thin films directly on the substrate distorts the crystal orientation and thanks to the seed layer for serving as a template for crystal growth. Here, we studied the non-collinear AFM material 𝑀𝑛3𝑆𝑛 systematically by varying the seed Ru layer deposition temperature and the post-annealing temperature of the stack (substrate/Ru(13 nm)/𝑀𝑛3𝑆𝑛(42 nm)) on 𝐴𝑙2𝑂3(0001) and 𝑀𝑔𝑂(111) substrates. The high-resolution X-ray diffraction (HRXRD) results prove their epitaxial relationship with the seed Ru layer on both substrates, as shown in Figure 1 (a). Observing higher-order diffraction and the Pendellösung signals suggests that interfaces are coherent in crystal growth2. The calculated out-of-plane lattice constant and the interplanar d-spacing as a function of the mentioned variables corroborate the plausible strain, which ascertains the rocking curve results. It is observed that crystal distribution, hence called mosaicity, is qualitatively larger on 𝑀𝑔𝑂 substrate than on 𝐴𝑙2𝑂3 substrate as shown in Figure 1 (b). The calculated strain along the growth direction manifests the growth-induced strain due to lattice mismatch. The calculated strain values compared with the bulk values suggest that the strain is larger on 𝑀𝑔𝑂 than that of the 𝐴𝑙2𝑂3 substrate. The static magnetic measurements data indicate that the order parameter can be modulated by controlling the strain via post-annealing temperature conditions. The observed strain-dependent magnetization establishes the piezo-magnetism3. Our systematic investigation on seed Ru-assisted epitaxial growth provides a comprehensive understanding of the viable route towards the fabrication of piezo-magnetic devices.
