Unpaired Spin Populations and Spin‐Pairing Tendencies of the Nonequivalent Vanadium Sites of the Magnetic Metal NaV6O11 Investigated by Electronic Band Structure Calculations and Spin Dimer Analysis.

Abstract

The unpaired spin populations and spin-pairing tendencies of the three different vanadium atoms of NaV6O11 above and below its trimerization temperature Tt = 245 K were examined by determining, as a function of the number of unpaired spins per formula unit, N, the total energies of NaV6O11 as well as the 3d orbital populations of the V(1), V(2), and V(3) atoms on the basis of first-principles spin-polarized electronic band structure calculations. Spin dimer analysis was also carried out to estimate the spin-pairing tendencies of the V(1) and V(2) sites above and below Tt. Our work does not support the heuristic assumptions employed to interpret the magnetic properties of NaV6O11 as well as its analogues SrV6O11 and PbV6O11. States with a wide range of N values (i.e., ∼4 < N < ∼9) are expected to contribute to the magnetic properties of NaV6O11 above and below Tt. The V(1), V(2), and V(3) atoms differ mainly in the extents of their spin polarizations but not in their oxidation states. The unpaired spin pop...