Degree Type

Dissertation

Date of Award

1986

Degree Name

Doctor of Philosophy

Department

Physics and Astronomy

Abstract

An interpolation scheme for the band structure of paramagnetic iron was used to model the band structure of ferromagnetic iron. This was carried out by superimposing two paramagnetic iron band structures with a 2.2 eV energy offset to simulate the exchange split- ting. This model was used to calculate the optical conductivity of ferromagnetic iron. Good agreement was achieved between these results and the optical conductivity calculated from first-principles by Callaway and Wang.('1) This demonstrates the validity and the useful- ness of an interpolation scheme for calculating quantities dependent on electronic structure. The broad peak in the iron optical conductiv- ity ((sigma)(,1)) at 2.5 eV is found to be due to transitions from minority-spin bands 2 and 3 to minority-spin bands 4 and 5 at locations throughout the interior of the Brillouin zone, but generally not on or near symme- try lines and points. The broad 6.0 eV peak in (sigma)(,1) is found to be due to the two two-dimensional band gap minimums near the middle of the (DELTA) and (LAMDA) symmetry lines. These transitions occur in both the minority- and majority-spin band structures;Composition modulation spectroscopy was applied to iron using aluminum as a dilutant. Two characteristic features were present in the resulting (DELTA)(epsilon)(,2) spectra. These were a broad negative peak at 2.5 eV and a broad positive peak at 6 eV--the same locations as the peaks in (sigma)(,1). The decrease in (epsilon)(,2) at 2.5 eV is attributed to a depletion of electronic states in the host d bands. This depletion is mainly due to the valence difference between iron and aluminum. The increase;in (epsilon)(,2) at 6 eV is claimed to be due to band narrowing and/or the presence of a virtual bound state residing below the iron d bands; *DOE Report IS-T-1238. This work was performed under contract No. W-7405-Eng-82 with the U.S. Department of Energy. ('1)J. Callaway and C. S. Wang, Phys. Rev. B16, 2095 (1977).

DOI

https://doi.org/10.31274/rtd-180813-11930

Publisher

Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/

Copyright Owner

Joseph Holmes Sexton

Language

en

Proquest ID

AAI8703765

File Format

application/pdf

File Size

99 pages

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