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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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|
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