Regensburg 2010 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 37: MLT: Poster Session

TT 37.7: Poster

Donnerstag, 25. März 2010, 14:00–18:00, Poster A

Dielectric spectroscopy on magnetically doped relaxor ferroelectrics — •Daniel Niermann and Joachim Hemberger — 2. Physikalisches Institut, Universität zu Köln

Materials showing a mutual dependence between magnetization and electric polarization in external fields got into the focus of recent research during the last years, not at least due to possible technical applications. It was recently shown that magnetoelectric behaviour can not only be observed in materials exhibiting long-range ferromagnetic and ferroelectric orders, so called multiferroics, but also in disordered multiglasses with two different glassy states. We performed Fe-doping on the B-sites (Ti⁴⁺) of the host crystal SrTiO₃, while adjusting the over-all valency by simultaneous doping of non-magnetic La³⁺-ions on the A-sites. For increased doping a transition from quantum-paraelectric to relaxor-ferroelectric behaviour is expected. Polycrystalline samples of Sr_1−xLa_xTi_1−xFe_xO₃ (x = 0.01, 0.05, 0.10) were prepared by a standard ceramic process and characterized by x-ray diffractometry, REM-EDX and measurements of magnetic susceptibility. Relaxor-states and field dependent dielectric properties of the sample-compound were studied by broadband dielectric spectroscopy. The measurements were performed down to low temperatures using an impedance-analyser and a standard two electrode parallel-plate capacitor geometry.