Issue
EPL
Volume 80, Number 2, October 2007
Article Number 27002
Number of page(s) 6
Section Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties
DOI http://dx.doi.org/10.1209/0295-5075/80/27002
Published online 19 September 2007
EPL, 80 (2007) 27002
DOI: 10.1209/0295-5075/80/27002

Magnetodielectric effect and optic soft mode behaviour in quantum paraelectric EuTiO3 ceramics

S. 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

Abstract
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.

PACS
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