Accession Number:

ADA010544

Title:

The Effect of Exchange on the Theory of the Order-Disorder and the Insulator-Metal Transitions in Magnetite, Fe3O4.

Descriptive Note:

Final rept.,

Corporate Author:

NAVAL SURFACE WEAPONS CENTER WHITE OAK LAB SILVER SPRING MD

Personal Author(s):

• Tanaka,Tomoyasu
• Chen,Charles
• Libelo,Louis F.

Report Date:

1975-04-01

Pagination or Media Count:

36.0

Abstract:

Using a Hartree-Fock decoupled Hamiltonian, electronic energy bands for magnetite, Fe3O4 have been determined at temperatures in the neighborhood of the Verwey transition temperature. The cluster-variation method has been applied to determine the parameters appearing in the Hartree-Fock Hamiltonian. It was observed that the insulator-metal transition takes place at a temperature where the Verwey order is still finite although it is quite small. As long as the Verwey transition persists as a second order transition the theory here predicts two different distinct transition temperatures, one for the insulator-metal transition and the other for the order-disorder transition.

Descriptors:

• *BAND THEORY OF SOLIDS
• *IRON OXIDES
• *MAGNETITE
• PHASE TRANSFORMATIONS
• ENERGY GAPS
• TRANSITION TEMPERATURE
• ENERGY BANDS
• HARTREE FOCK APPROXIMATION

Subject Categories:

• Solid State Physics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE