Spectroscopic detection of hopping induced mixed valence for Ti and Sc in GdSc1-xTixO3 for x > 0.165.
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.
North Carolina State University, Raleigh, NC, 27695-8202, USA.
Gerald
G
Lucovsky
Leonardo
L
Miotti
Karen Paz
KP
Bastos
Carolina
C
Adamo
Darrell G
DG
Schlom
D004579:Electron Transport; D060526:Magnetic Fields; D008422:Materials Testing; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D010087:Oxides / Q000737:chemistry*; D010316:Particle Size; D013057:Spectrum Analysis / Q000379:methods*; D028561:Transition Elements / Q000737:chemistry*
D010087:Oxides; D028561:Transition Elements