Eur. Phys. J. B 12, 199-207 (1999)
https://doi.org/10.1007/s100510050996

Spin-spin correlations in the insulating and metallic phases of the Mott system V₂O₃

¹ Department of Physics, Loughborough University, Leicester LE11 3TU, UK
² Institut Laue-Langevin, BP 156, 38042 Grenoble Cedex 9, France
³ Institut für Theoretische Physik, RWTH Aachen, Templergraben 55, 52056 Aachen, Germany
⁴ Max-Planck-Institut für Festkörperforschung, Heisenberg Straße 1, 70506 Stuttgart, Germany

Corresponding author: ^a K.R.Ziebeck@lboro.ac.uk

Received: 7 April 1999
Published online: 15 November 1999

Abstract

The magnetic response in has been investigated using polarised neutron scattering with polarisation analysis. Measurements were carried out at three temperatures corresponding to the antiferromagnetic insulating ground state, the metallic phase and the high temperature metallic phase. At the first order metal insulator transition there is a dramatic change in the magnetic response with the metallic and high temperature metallic phases being characterised by ferromagnetic spatial correlations of the paramagnetic response. The establishment of ferromagnetic correlations at the metal insulator transition accounts for the abrupt jump in the uniform susceptibility. It is proposed that the differentiation of the V-V distances across the edges of octahedra is of critical importance for the change in electronic conductivity but also for the establishment of the spatial correlations. The gradual high temperature evolution of the conductivity then occurs by the reduction in the vanadium d overlap brought about by thermal expansion. The first order reduction in atomic volume which occurs on the establishment of the metallic phase results from an instability of the vanadium local moment arising from the change in electronic structure.