Berlin 2015 – wissenschaftliches Programm

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DF: Fachverband Dielektrische Festkörper

DF 8: High-k and Low-k Dielectrics (DS with DF)

DF 8.1: Vortrag

Dienstag, 17. März 2015, 11:15–11:30, H 0111

Broadband dielectric response of doped rutile: intrinsic or extrinsic colossal dielectric constants? — •Martin Wohlauer, Stephan Krohns, Peter Lunkenheimer, and Alois Loidl — Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg (Germany)

Materials exhibiting so-called colossal effects have an enormous potential for future use in correlated electronics, including capacitors for energy storage and integrated circuits. The search for functional ceramics showing colossal dielectric constants (CDC) is still an active field of research¹. Different phenomena, e.g., charge-order or internal as well as external electrical heterogeneities can lead to CDCs². For the most prominent ceramic, CaCu₃Ti₄O₁₂, the mechanism giving rise to a dielectric permittivity of up to 10⁵ is of extrinsic nature, e.g. interface polarisation. The discovery of CDCs in indium- and niobium-doped rutile at room temperatures recently also attracted high scientific interest³. In this talk, broadband dielectric measurements on various doped rutile ceramics will be presented. The results will be thoroughly discussed, especially emphasizing the contributions of external and internal interface effects influencing the permittivity. We demonstrate, that extrinsic interface effects are responsible for the CDCs in doped rutile.