Spectroscopic detection of hopping induced mixed valence for Ti and Sc in GdSc1-xTixO3 for x > 0.165

J Nanosci Nanotechnol. 2012 Jun;12(6):4749-56. doi: 10.1166/jnn.2012.4911.

Abstract

Only two of the first row transition metals have elemental oxides that are either ferro- or ferri-magnetic. These are CrO2 and Fe3O4. The electron spin alignment that promotes the ferro(i)magnetism is associated with a double exchange mechanism that requires mixed valence as well as metallic conductivity. This paper describes a novel way to realize these two necessary, but not sufficient conditions for double exchange magnetism. These are mixed valence and a hopping conductivity that promotes at least intra-plane electron spin alignment in a complex oxide perovskite host, A(B,C)O3. A is an ordinary metal, or a rare earth atom, B is a d0 transition metal, and C is a d(n) transition metal in which n > or = 1, as for example in GdSc1-xTi(x)O3. This article combines X-ray absorption spectroscopy, multiplet theory, charge transfer multiplet theory and degeneracy removal by Jahn-Teller effect mechanisms to demonstrate mixed valence for both Sc and Ti above a percolation threshold, x > 0.16, in which hopping transport gives rise to a metal to insulator transition.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Electron Transport
  • Magnetic Fields
  • Materials Testing
  • Nanostructures / chemistry*
  • Nanostructures / ultrastructure*
  • Oxides / chemistry*
  • Particle Size
  • Spectrum Analysis / methods*
  • Transition Elements / chemistry*

Substances

  • Oxides
  • Transition Elements