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Magnetic ordering in Garfield nontronite under applied magnetic fields

Published online by Cambridge University Press:  09 July 2018

E. Murad
Affiliation:
Lehrstuhl für Bodenkunde, Technische Universität München, D-8050 Freising-Weihenstephan, Federal Republic of Germany
J. D. Cashion
Affiliation:
Department of Physics, Monash University, Clayton, Victoria 3168, Australia
L. J. Brown
Affiliation:
Lehrstuhl für Bodenkunde, Technische Universität München, D-8050 Freising-Weihenstephan, Federal Republic of Germany

Abstract

Mössbauer spectra of Garfield nontronite H33a were taken at temperatures between 2·5 and 37 K under longitudinally applied magnetic fields up to 9 T. While no magnetic order was apparent in the absence of an applied field above 7 K, the application of external magnetic fields led to the induction of magnetic hyperfine splitting up to at least 19 K. Variation of the applied fields allowed determination of hyperfine fields of bulk nontronite, and indicated the bulk sample to have a Néel temperature of about 20 K. The non-ideal behaviour of this nontronite, leading to the lack of magnetic order in the absence of applied magnetic fields, is in line with the frustration of antiferromagnetic order in the octahedral sheets due to the presence of about 6% of the iron content in tetrahedral sites, although some influence of magnetic dilution cannot be excluded.

Type
Research Article
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1990

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