Giant dielectric permittivity and electromechanical strain in thin film materials produced by pulsed-laser deposition

Thin film materials with a giant dielectric permittivity er′≈10 000 and an electromechanical strain of Δh/h≈8% are produced by pulsed-laser deposition. Composite targets containing various different oxides such as BaTiO3, BaO2, BaCO3, and TiO2 powder embedded in the polymer polytetrafluoroethylen (PTFE) are employed for laser ablation. The dielectric permittivities of the films show strong relaxation at frequencies above 10 kHz, a pronounced dependence on layer thickness, and a frequency-dependent activation at lower temperatures. Composite targets as well as films produced from BaF2/PTFE targets show only low permittivities with er′<20 and do not reveal such phenomena.