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DF: Fachverband Dielektrische Festkörper
DF 18: Applications of dielectric solids
DF 18.2: Talk
Thursday, March 17, 2011, 16:20–16:40, MÜL Elch
Colossal Dielectric Constants in Transition-Metal Oxides — •Stephan Krohns1,2, Peter Lunkenheimer1, and Alois Loidl1,2 — 1Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, Germany — 2Institute for Materials Resource Management, University of Augsburg, Germany
Systems showing so-called colossal effects have an enormous potential as building blocks for future correlated electronics, including capacitors for energy storage and integrated circuits. For example, in the past decade the generation and investigation of very-high ("colossal") dielectric constants (CDC) has been an active field of basic and applied research. The measurement of the dielectric response to ac electric fields is one of the most powerful techniques to provide detailed insight into the underlying physics responsible for CDCs, which may comprise very different phenomena, e.g., charge order, molecular or polaronic relaxations, hopping charge transport, ferroelectricity or density-wave formation. Most of the materials exhibiting these effects, among them numerous transition-metal oxides [1], have complex ground states emerging from strong electronic correlations. For example, charge-ordered La2−xSrxNiO4 exhibits CDCs up to gigahertz frequencies at room temperature [2]. Here, we thoroughly discuss the mechanisms that can lead to colossal values of the dielectric constant in transition-metal oxides, especially emphasising effects generated by external and internal interfaces, including electronic phase separation.
[1] P. Lunkenheimer et al., Eur. Phys. J. Special Topics 180, 61 (2010). [2] S. Krohns et al., Appl. Phys. Lett. 94, 122903 (2009).