First-principles investigations on the magnetic structure of α-NaMnO₂.

α-NaMnO(2) contains layers of high spin Mn(3+) (d(4)) ions parallel to the ab plane, and Mn(3+) layers alternate with Na(+) ions layers along the c direction. To explore the interesting two-dimensional spin correlations and one-dimensional magnetic excitations, we carefully studied the electronic and magnetic properties of α-NaMnO(2) via density functional theory calculations. By evaluating the intra-layer interactions J(1)-J(4) as well as the inter-layer exchanges J(5) and J(6) through performing mapping analysis, we found that α-NaMnO(2) displays typical two-dimensional spin correlations, which are dominated by the intra-chain interaction J(1) and the inter-chain interaction J(3) (J(3)/J(1) ≈ 0.21). Interestingly, both the strong spin exchange interactions J(1) and J(3) come from supersuperexchange (SSE), other than superexchange (SE). Also, due to the topology of the lattices, the magnetic excitation is dominated by the intra-chain interaction J(1), leading to the one-dimensional model.