Spin dimer analysis of the magnetic structures of A2V3O9 (A = Ba, Sr) and η-Na9V14O35: Importance of the V4+–O⋯O–V4+ super-superexchange interactions mediated by the O–V5+–O bridges

Spin dimer analysis was carried out for the magnetic oxides of V4+ (d1) ions, A2V3O9 (A = Ba, Sr) and η-Na9V14O35, to account for their magnetic structures. After identifying the V(Oeq)4 square planes containing the magnetic orbitals of the V4+ (d1) ions, we analyzed the relative strengths of the various V–Oeq–V and V–Oeq⋯Oeq–V spin exchange interactions. The V–Oeq⋯Oeq–V spin exchange interactions mediated by Oeq–V5+–Oeq bridges are found to be crucial in determining the magnetic structures of A2V3O9 (A = Ba, Sr) and η-Na9V14O35. Our analysis suggests that η-Na9V14O35 should have two different spin gaps.

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