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Brillouin scattering studies in $Fe_{3}O_{4}$ across the Verwey transition

Seikh, Motin Md and Narayana, Chandrabhas and Metcalf, PA and Honig, JM and Sood, AK (2005) Brillouin scattering studies in $Fe_{3}O_{4}$ across the Verwey transition. In: Physical Review B, 71 (17).

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Abstract

Brillouin scattering studies have been carried out on high quality single crystals of $Fe_{3}O_{4}$ with [100] and [110] faces in the temperature range of 300-30 K. The room temperature spectrum shows a surface Rayleigh wave (SRW) mode at 8 GHz and a longitudinal acoustic (LA) mode at 60 GHz. The SRW mode frequency shows a minimum at the Verwey transition temperature $T_{V}$ of 123 K. The softening of the SRW mode frequency from about 250 K to $T_{V}$ can be quantitatively understood as a result of a decrease in the shear elastic constant $C_{44}$, arising from the coupling of shear strain to charge fluctuations. On the other hand,the LA mode frequency does not show any significant change around $T_{V}$,but shows a large change in its intensity. The latter shows a maximum at around 120 K in the cooling run and at 165 K in the heating run,exhibiting a large hysteresis of 45 K. This significant change in intensity may be related to the presence of stress-induced ordering of $Fe^{3+}$ and $Fe^{2+}$ at the octahedral sites, as well as to stress-induced domain wall motion.

Item Type: Journal Article
Additional Information: Copyright for this article belongs to American Physical Society.
Department/Centre: Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited: 29 Jul 2005
Last Modified: 19 Sep 2010 04:19
URI: http://eprints.iisc.ernet.in/id/eprint/3470

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