Spin dimer analysis of the magnetic structures of A(2)V(3)O(9) (A = Ba, Sr) and eta-Na9V14O35: Importance of the V4+-O center dot center dot center dot O-V4+ super- superexchange interactions mediated by the O-V5+-O bridges

摘要

Spin dimer analysis was carried out for the magnetic oxides of V4+ (d(1)) ions, A(2)V(3)O(9) (A = Ba, Sr) and eta-Na9V(14)O(35), to account for their magnetic structures. After identifying the V(Oeq)(4) square planes containing the magnetic orbitals of the V4+ (d(1)) ions, we analyzed the relative strengths of the various V-Oe(q)-V and V-O-eq center dot center dot center dot O-eq-V spin exchange interactions. The V-O-eq center dot center dot center dot O-eq-V spin exchange interactions mediated by O-eq-v(5+)-O-eq bridges are found to be crucial in determining the magnetic structures of A2V3O9 (A = Ba, Sr) and eta-Na9V14O35. Our analysis suggests that eta-Na9V14O35 should have two different spin gaps. (c) 2007 Elsevier Masson SAS. All rights reserved.