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DF: Fachverband Dielektrische Festkörper

DF 4: Multiferroics, Phase Transitions & Relaxors

DF 4.2: Talk

Monday, March 23, 2009, 10:40–11:00, WIL B321

Multiglassy systems based on incipient ferroelectrics — •Vladimir Shvartsman¹, Pavel Borisov¹, Subhankar Bedanta¹, Aleksander Tkach², Paula Vilarinho², and Wolfgang Kleemann¹ — ¹Angewandte Physik, Universität Duisburg-Essen, Lotharstr. 1, 47048 Duisburg, Germany — ²Department of Ceramics and Glass Engineering, CICECO, University of Aveiro, 3810-193, Aveiro, Portugal

In recent years there has been growing scientific interest in materials exhibiting the magnetoelectric (ME) effect. Research has mainly been focused on multiferroic materials, where two or more ferroically ordered states exist simultaneously. We show that the class of ME materials may be extended to those, where two glassy states of different nature occur simultaneously. This can be realized in incipient ferroelectrics like SrTiO₃ or KTaO₃ moderately doped with a paramagnetic cation, e.g. with Mn²⁺ [1]. The transitions into glassy states manifest themselves by anomalies in the temperature dependencies of the dielectric and magnetic susceptibilities as well as by a particular memory effects (”hole burning”). The ME effects were directly measured using a modified SQUID susceptometer. Although the amount of magnetically active ions is relatively small, a strong higher order ME coupling via both the ”paramagnetoelectric” EH² and the ”magneto-capacitive” E²H² effects is observed.

[1] V.V. Shvartsman, S. Bedanta, P. Borisov, W. Kleemann, A. Tkach, P.M. Vilarinho, Phys. Rev. Lett. 101 (2008) 165704.