Glassy dielectric response in Tb2NiMnO6 double perovskite with similarities to a Griffiths phase

Nhalil, Hariharan and Nair, Harikrishnan S and Bhat, HL and Elizabeth, Suja (2013) Glassy dielectric response in Tb2NiMnO6 double perovskite with similarities to a Griffiths phase. In: EPL, 104 (6).

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Abstract

Results of frequency-dependent and temperature-dependent dielectric measurements performed on the double-perovskite Tb2NiMnO6 are presented. The real (epsilon(1)(f,T)) and imaginary (epsilon(2)(f,T)) parts of dielectric permittivity show three plateaus suggesting dielectric relaxation originating from the bulk, grain boundaries and the sample-electrode interfaces, respectively. The epsilon(1)(f,T) and epsilon(2)(f,T) are successfully simulated by a RC circuit model. The complex plane of impedance, Z'-Z `', is simulated using a series network with a resistor R and a constant phase element. Through the analysis of epsilon(f,T) using the modified Debye model, two different relaxation time regimes separated by a characteristic temperature, T*, are identified. The temperature variation of R and C corresponding to the bulk and the parameter alpha from modified Debye fit lend support to this hypothesis. Interestingly, the T* compares with the Griffiths temperature for this compound observed in magnetic measurements. Though these results cannot be interpreted as magnetoelectric coupling, the relationship between lattice and magnetism is markedly clear. We assume that the observed features have their origin in the polar nanoregions which originate from the inherent cationic defect structure of double perovskites. Copyright (C) EPLA, 2013

Item Type:	Journal Article
Publication:	EPL
Publisher:	EPL ASSOCIATION, EUROPEAN PHYSICAL SOCIETY
Additional Information:	Copyright for this article belongs to the EPL ASSOCIATION, FRANCE
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	07 Mar 2014 07:23
Last Modified:	07 Mar 2014 07:26
URI:	http://eprints.iisc.ac.in/id/eprint/48504

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