Electronic Structure of Transition Metal Compounds as Studied by High Energy Spectroscopies

Abstract

Compounds of the 3d transition metals exhibit an astonishing variety of physical properties both electrical and magnetic [1-3]. The electrical properties range from large band gap insulators (v2o5, cr2o3, α-Fe2o3) and ferroelectrics (BaTiO3) to semiconductors (Cu2O, FeS2, MnS) and via semiconductor metal transitions (V02, V2O3, Fe3O4, Ti2O3) to metals (CrO2, NiS, CuS) and even superconductors (La2-xBaxCu04, YBa2Cu307). In magnetism we find antiferromagnets (α-Fe2O3, NiO, CoO, MnO) ferrimagnets (γ-Fe2O3, ferrites and garnets) and ferromagnets (CrO2). Many of these materials have been and are of great importance in various applications because their properties can be tailored and fine tuned with chemical substitutions to, for example, optimize the magnetic anisotropy or the compensation on Neel temperature. Perhaps the most astonishing example of how extremely sensitive the properties can be to the details of the chemical composition is provided by the high Tc superconductors. Here a change of x in La2-xBaxCu04 or the stoichiometry in YBa2Cu307-δ turns an antiferromagnetic insulator into a high temperature superconductor. The reason for this wide range of properties must lie in the sensitivity of the electronic structure to the details of the crystal structure, the chemical composition and the stoichiometry.KeywordsCrystal FieldCore HoleCharge FluctuationTransition Metal CompoundCrystal Field SplittingThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.