On the Nature of the Magnetic Ground-State Wave Function of V₂O₃

Abstract

After a brief historical introduction, we dwell on two recent experiments in the low-temperature, monoclinic phase of V2O3: K-edge resonant x-ray scattering and non-reciprocal linear dichroism, whose interpretations are in conflict, as they require incompatible magnetic space groups. Such a conflict is critically reviewed, in the light of the present literature, and new experimental tests are suggested, in order to determine unambiguously the magnetic group. We then focus on the correlated, non-local nature of the ground-state wave function, that is at the basis of some drawbacks of the LDA+U approach: we singled out the physical mechanism that makes LDA+U unreliable, and indicate the way out for a possible remedy. Finally we explain, by means of a symmetry argument related to the molecular wave function, why the magnetic moment lies in the glide plane, even in the absence of any local symmetry at vanadium sites.

Variational study of the antiferromagnetic insulating phase ofV2O3based onNthorder muffin-tin-orbitals

“…In a previous publication 25 , one of us has already highlighted the main drawbacks of implementation of DFT-based ab-initio methods to V 2 O 3 . This compound is a very peculiar strongly correlated system, in which non-local correlations play an important role.…”

Antiferromagnetic–paramagnetic insulating transition in Cr-doped V2O3investigated by EXAFS analysis

“…Moreover, the introduction of a molecular spin, i.e. a spin state whose wavefunction extends over the whole molecule, can explain the absence of a spin component out of the glide plane on the basis of symmetry considerations [41], and the change in the orbital occupancy in the molecular wavefunction allows one to explain even the linear dichroism experiment of [10] (see figure 15 of [16]). The PI/AFI transition is described in such a model as an order-to-disorder transition, where each molecule can fluctuate in the high temperature phase between three positions that correspond to the three a priori equivalent monoclinic distortions of the molecule.…”