Dielectric properties of strained (Sr,Ca)TiO3/(Ba,Sr)TiO3 artificial lattices

Abstract

Dielectricsuperlattices of (Sr,Ca)TiO 3 /(Ba,Sr)TiO 3 have been formed by a pulsed laserablation technique. The crystal structure is controlled with atomic order accuracy and a large lattice stress of 0.5–1 GPa can be introduced periodically at the interfaces owing to the lattice mismatch of the constituent layers. The (Sr 0.3 Ba 0.7 )TiO 3 /(Sr 0.48 Ca 0.52 )TiO 3 superlattice shows dramatically large dielectric constant of 900 even at film thickness of 500 Å. The optimum pressure for inducing tetragonality in the (Ba,Sr)TiO 3 layers and enhanced dielectric properties occurs at a lattice mismatch of 2.5–3%.