Please use this identifier to cite or link to this item: http://lib.jncasr.ac.in:8080/jspui/handle/10572/314
Title: A Brillouin study of the temperature-dependence of the acoustic modes across the insulator–metal transitions in V2O3 and Cr-doped V2O3
Authors: Seikh, Md Motin
Narayana, Chandrabhas
Sood, A K
Murugavel, P
Kim, M W
Metcalf, P A
Honig, J M
Rao, C N R
Keywords: acoustic phonons
metal–insulator transition
surface acoustic waves
Brillouin scattering
Phase Transition
Scattering
(V1-XCRX)2O3
Pressure
Crystals
Silicon
Spin
Issue Date: Jun-2006
Publisher: Pergamon Elsevier Science Ltd
Citation: Solid State Communications 138(9), 466–471 (2006)
Abstract: Brillouin scattering studies have been carried out on high-quality single crystals of undoped and 0.9% Cr-doped V2O3. The observed modes in both the samples at not, vert, similar12 and not, vert, similar60 GHz are associated with the surface Rayleigh wave (SRW) and bulk acoustic wave (BAW), respectively. In the undoped sample, the mode frequencies of the SRW and BAW modes decrease as the temperature is lowered from room temperature to the insulator–metal transition temperature (TIM=TN=not, vert, similar130 K). Below the transition, the modes show hardening. In the doped sample, the SRW mode shows a similar temperature-dependence as the undoped one, but the BAW mode shows hardening from room temperature down to the lowest temperature (50 K). This is the first measurement of the sound velocity below TIM in the V2O3 system. The softening of the SRW frequency from 330 K to TIM can be qualitatively understood on the basis of the temperature-dependence of C44, which, in turn, is related to the orbital fluctuations in the paramagnetic metallic phase. The hardening of the mode frequencies below TIM suggests that C44 must increase in the antiferromagnetic insulating phase, possibly due to the orbital ordering.
Description: Restricted Access
URI: http://hdl.handle.net/10572/314
Other Identifiers: 0038-1098
Appears in Collections:Research Papers (Prof. C.N.R. Rao)

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