Temperature-dependent infrared reflectivity studies of multiferroic TbMnO3: Evidence for spin-phonon coupling

Kumar, Pradeep and Saha, Surajit and Serrao, CR and Sood, AK and Rao, CNR (2010) Temperature-dependent infrared reflectivity studies of multiferroic TbMnO3: Evidence for spin-phonon coupling. In: Pramana, 74 (2). pp. 281-291.

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Abstract

We have measured near normal incidence far-infrared (FIR) reflectivity spectra of a single crystal of TbMnO3 from 10 K to 300 K in the spectral range of 50 cm(-1)-700 cm(-1). Fifteen transverse optic (TO) and longitudinal optic (LO) modes are identified in the imaginary part of the dielectric function epsilon(2)(omega) and energy loss function Im(-1/epsilon(omega)), respectively. Some of the observed phonon modes show anomalous softening below the magnetic transition temperature T-N (similar to 46 K). We attribute this anomalous softening to the spin-phonon coupling caused by phonon modulation of the superexchange integral between the Mn3+ spins. The effective charge of oxygen (Z(O)) calculated using the measured LO-TO splitting increases below TN.

Item Type:	Journal Article
Additional Information:	Copyright of this article belongs to Indian Academy of Sciences.
Keywords:	Spin-phonon coupling; longitudinal and transverse optic modes; effective charge; energy loss function
Department/Centre:	Division of Chemical Sciences > Materials Research Centre Division of Physical & Mathematical Sciences > Physics
Date Deposited:	24 Mar 2010 09:15
Last Modified:	19 Sep 2010 05:57
URI:	http://eprints.iisc.ernet.in/id/eprint/26382

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