A Mössbauer Spectral Study of the GdCo₄₋ₓFeₓB Compounds

Author

Fernande Grandjean, Missouri University of Science and TechnologyFollow
Raphäel P. Hermann
Eustachy S. Popiel
Gary J. Long, Missouri University of Science and TechnologyFollow

Abstract

The iron-57 Mössbauer spectra of the GdCo_4-xFe_xB compounds, where x is 0.10, 0.15, 0.20, 0.25, 1, 2, 2.5, and 2.6, have been measured at room temperature and reveal relatively small iron hyperfine fields of approximately 12-18 T, relatively large quadrupole interactions of approximately +0.9 and -1 mm/s, and three very different types of spectra for x=0.10 and 0.15, x=0.25, 1, and 2, and x=2.5 and 2.6. The differences result from both the different easy magnetization directions in these compounds and the different cobalt and/or iron occupancies of the crystallographic 2c and 6i sites. The spectra have been fitted by calculating the spectral absorption with the complete iron-57 nuclear excited state Hamiltonian for the iron 2c and 6i sites. The fits have used an asymmetry parameter eta and Euler angles θ and φ that relate the hyperfine field to the iron electric field gradient axes of each crystallographic site in an orientation that is consistent with the structural and magnetic properties of the site. The results of the fits indicate both that the full Hamiltonian approach is required for physically reasonable spectral fits and that the small observed fields result from the presence of large orbital contributions which subtract from the Fermi contact contributions to the magnetic hyperfine fields of the two sites. The iron 2c occupancy obtained from the Mössbauer spectral area has been used to model the compositional dependence of the magnetic anisotropy constant in the GdCo_4-xFe_xB compounds.

Recommended Citation

F. Grandjean et al., "A Mössbauer Spectral Study of the GdCo₄₋ₓFeₓB Compounds," Journal of Applied Physics, vol. 101, no. 2, American Institute of Physics (AIP), Jan 2007.

The definitive version is available at https://doi.org/10.1063/1.2400115

Department(s)

Chemistry

Keywords and Phrases

Iron Hyperfine Fields; Nuclear Excited State; Quadrupole Interactions; Room Temperature; Cobalt; Crystallography; Hamiltonians; Iron; Magnetization; Mössbauer Spectroscopy; Gadolinium Compounds

International Standard Serial Number (ISSN)

0021-8979

Document Type

Article - Journal

Document Version

Final Version

File Type

text

Language(s)

English

Rights

© 2007 American Institute of Physics (AIP), All rights reserved.

Publication Date

01 Jan 2007