Magnetodielectric effect and optic soft mode behaviour in quantum paraelectric EuTiO3 ceramicsS. Kamba1, D. Nuzhnyy1, P. Vanek1, M. Savinov1, K. Knízek1, Z. Shen2, E. Santavá1, K. Maca3, M. Sadowski4 and J. Petzelt1
1 Institute of Physics ASCR - v.v.i. Na Slovance 2, 182 21 Prague 8, Czech Republic
2 Arrhenius Laboratory, Stockholm University - SE-10691 Stockholm
3 Brno University of Technology - Technicka 2896/2, 616 69 Brno, Czech Republic
4 Grenoble High Magnetic Field Lab, CNRS - 25, avenue des Martyrs, Grenoble Cedex 9, France
received 20 July 2007; accepted in final form 29 August 2007; published October 2007
published online 19 September 2007
Infrared reflectivity and time-domain terahertz transmission spectra of EuTiO3 ceramics revealed a polar optic phonon at 6-300 K whose softening is fully responsible for the recently observed quantum paraelectric behaviour. Even if our EuTiO3 ceramics show lower permittivity than the single crystal due to a reduced density and/or small amount of secondary pyrochlore Eu2Ti2O7 phase, we confirmed a magnetic field dependence of the permittivity, also slightly smaller than in single crystal. An attempt to reveal the soft phonon dependence at 1.8 K on the magnetic field up to 13 T remained below the accuracy of our infrared reflectivity experiment.
75.80.+q - Magnetomechanical and magnetoelectric effects, magnetostriction.
78.30.-j - Infrared and Raman spectra.
63.20.-e - Phonons in crystal lattices.
© Europhysics Letters Association 2007