A giant low-frequency, in-plane dielectric constant, ∈ ∼ 10 6, for epitaxial thin films of Ca 1-xLa xMnO 3 (x≤0.03) was observed over a broad temperature range, 4 K≤T≤300 K. This phenomenon is attributed to an internal barrier-layer capacitor (IBLC) structure, with Schottky contacts between semiconducting grains. The room-temperature ∈ increases substantially with electron (La) doping, consistent with a simple model for IBLCs. The measured values of ∈ exceed those of conventional two-phase IBLC materials based on (Ba, Sr)TiO 3 as well as on recently discovered CaCu 3Ti 4O 12 and (Li,Ti)-doped NiO.
ASJC Scopus subject areas
- Physics and Astronomy(all)