Theoretical study of SrRu2O6 and related compounds

We theoretically investigate the electronic property of a hexagonal compound SrRu$_2$O$_6$ and isostructural CaOs$_2$O$_6$ [1]. Here, we focus on the topological property of these compounds under various strain conditions. Based on an analysis of parity eigenvalues, we anticipate that a three-dimensional strong topological insulating state should be realized when band inversion is induced at the A point in the hexagonal Brillouin zone. We found that such a transition is indeed possible in these compounds under certain strain conditions. In particular, for CaOs$_2$O$_6$, the transition could be induced more easily than SrRu$_2$O$_6$ owing to the stronger spin-orbit coupling and smaller lattice constants. We also investigate the magnetic property of SrRu$_2$O$_6$ using density functional theory. Detailed comparison with experimental reports [2,3] will be presented. [1] M. Ochi {\it et al.}, Phys. Rev. B {\bf 93}, 195149 (2016). [2] W. Tian {\it et al.}, Phys. Rev. B {\bf 92}, 100404(R) (2015). [3] C. I. Hiley {\it et al.}, Phys. Rev. B {\bf 92}, 104413 (2015).