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

alpha-NaMnO2 contains layers of high spin Mn3+ (d(4)) ions parallel to the ab plane, and Mn3+ 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 alpha-NaMnO2 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 alpha-NaMnO2 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) approximate to 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.