Theory for metal hydrides with switchable optical properties
- Department of Physics, University of Cincinnati, Cincinnati, Ohio 45221 (United States)
- Institute of Metal Physics, Russian Academy of Sciences, 620219, Ekaterinburg, GSP-170 (Russia)
- Theoretische Physik, ETH-Hoenggerberg, 8093 Zuerich (Switzerland)
Recently it has been discovered that lanthanum, yttrium, and other metal hydride films show dramatic changes in the optical properties at the metal-insulator transition. Such changes on a high-energy scale suggest the electronic structure is best described by a local model based on negatively charged hydrogen (H{sup {minus}}) ions. We develop a many-body theory for the strong correlation in a H{sup {minus}} ion lattice. The metal hydride is described by a large {ital U} limit of an Anderson lattice model. We use lanthanum hydride as a prototype of these compounds, and find that LaH{sub 3} is an insulator with a substantial gap consistent with experiments. It may be viewed either as a Kondo insulator or a band insulator due to strong electron correlation. A H vacancy state in LaH{sub 3} is found to be highly localized due to the strong bonding between the electron orbitals of hydrogen and metal atoms. Unlike the impurity states in the usual semiconductors, there is only weak internal optical transitions within the vacancy. The metal-insulator transition takes place in a band of these vacancy states. {copyright} {ital 1999} {ital The American Physical Society}
- OSTI ID:
- 321510
- Journal Information:
- Physical Review, B: Condensed Matter, Vol. 59, Issue 8; Other Information: PBD: Feb 1999
- Country of Publication:
- United States
- Language:
- English
Similar Records
Proton magnetic relaxation in lanthanum hydrides
Nuclear magnetic resonance study of the metal-nonmetal transition in lanthanum hydrides