On the Importance of the Interplaquette Spin Exchanges in Na_3RuO_4: Density Functional Theory Analysis of the Spin Exchange and Magnetic Properties

摘要

Na_3RuO_4 contains layers of high-spin Ru~(5+) d~3 ions grouped into isolated four-membered plaquettes, To determine the spin-lattice appropriate for Na_3RuO_4, we evaluated the intraplaquette exchanges J_1, J_2, and J_3 as well as the interplaquette exchanges J_4 and J_5 by performing mapping analysis based on first-principles density functional theory calculations. In addition, we examined how the trends in the calculated J_1-J_5 are related to the distortions of the RuO_6 octahedra in the four-membered plaquettes. The spin-lattice of Na_3RuO_4 is described by the intraplaquette exchanges J_1 and J_2 plus the interplaquette exchanges J_4 and J_5, with spin frustration arising from the (J_1, J_2, J_1) and (J_5, J_4, J_5) triangles. The trends in the calculated J_1-J_5 reflect the distortions of the RuO_6 octahedra in the four-membered plaquettes.