Orbitally Degenerate Binuclear Units

Depending on the thermal treatment of preparation, WV206 is either trirutile with a regular packing of the magnetic ions (vanadium(III)) and non-magnetic ones (tungsten (VI)) or rutile with a metal disorder [66, 67]. 

Such a behavior suggests, above TN, a description of the material in terms of discrete units. Clearly, the proposed model does explain the absence of significant anisotropy in spite of the local distortion at each site and the exchange contribution. In such examples, the distortions from the Oh symmetry constitute generally the driving force and lead to a high anisotropy of the magnetic properties. In fact, we have to describe here an unusual situation, in that the 

we show that the actual Hamiltonian may be expressed as  

Finally, the relative value of the exchange constants agree well with the theoretical estimate. Using the ionization potentials of the configurations V(II)-V(IV) corrected by polarization effects, and the spin-spin correlation energies determined from Racah parameters, we obtain b=0.36eV in two different ways thus ensuring the quality of the present model [67], 

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