PHOTOEMISSION AND OPTICAL STUDIES OF THE ELECTRONIC STRUCTURE OF NIO, COO, AND V204.
Abstract
The nature of the electronic states in the transition metal oxides has been the subject of controversy for some time. The difficulty arises because some of these oxides are insulators, and conventional band theory predicts that they should be metallic conductors because of their partially filled states. Models based on band theory, which have been proposed to explain this behavior, depend upon magnetic ordering. Localized models, on the other hand, explain the insulating nature as the result of weak interaction (small orbital overlap) of the metal ion d-electrons. Photoelectric emission and optical reflectance measurements have been performed on NiO, CoO, and V2O4 in order to determine details of their electronic structures and to examine the predictions of the theoretical models. Photoemission from these materials has been measured both above and below their magnetic transition temperatures. Details of experimental techniques are presented, including a new high-vacuum cleaving apparatus used for cleaving the NiO and CoO single crystals, and a method of preparing V2O4. From the results of these studies it is concluded that the highest lying filled states in the electronic structure of NiO and CoO are best represented by localized wave functions and that the various band models with magnetic ordering are not applicable to NiO or CoO. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1967
- Accession Number
- AD0835266
Entities
People
- R. J. Powell
Organizations
- Stanford University