Ferroelectric Properties in Heteroepitaxial Ba_0.6Sr_0.4TiO₃ Thin Films on SrRuO₃/SrTiO₃ Substrates

Abstract

Heteroepitaxial Ba0.6Sr0.4TiO3 thin films with thicknesses from 26 nm to 97 nm were grown on SrRuO3 bottom electrode films on SrTiO3 single crystal substrates. Although the films have a paraelectric composition, ferroelectric hysteresis was observed in displacement versus electric field (D–E) loops. The ferroelectricity is considered to be developed as a result of bi-axial stress, caused by lattice mismatch between the dielectric films and the bottom electrodes. The maximum difference in the displacement was over 0.4 C/m2, even when the thickness of the film was reduced to 26 nm. The hysteresis loops showed an asymmetric characteristic at a polarity of applied voltage. The asymmetry was discussed in terms of an asymmetrical deformation of the crystal structure, which is probably introduced during the heteroepitaxial growth.

Artificial ferroelectricity in perovskite superlattices

“…The lattice parameters of the ASLs were determined using reciprocal space mapping (BRUKER AXS, Dis-cover8). Abe et al [12][13][14] reported that the ferroelectricity of BTO/ STO solid solution films was enhanced by the anisotropic lattice distortion. Commercial high-frequency planar analysis software (SONNET EM) was used to design the interdigitalelectrode pattern and to calculate the dielectric permittivity from the complex admittance measured.…”

Investigation of Nonswitching Regions in Ferroelectric Thin Films Using Scanning Force Microscopy

“…9,10) If an in-plane lattice of a ferroelectric film is larger than that of the bottom electrode material, the preference for negative polarity of polarization over positive is created by the lattice deformation. As a result, nonswitching regions are formed in the ferroelectric thin film at the interfacial region near the bottom electrode.…”

Enhancement of Ferroelectric Curie Temperature in BaTiO3 Films via Strain‐Induced Defect Dipole Alignment

“…[ 10 ] In turn, these anomalous lattice expansions are associated with interesting changes in the physical properties including enhancement of the ferroelectric transition temperature [ 7,11,13 ] and voltage-shifted ferroelectric hysteresis loops where the voltage shift scales linearly with thickness. [ 8,13,14 ] Despite this range of interesting work, no clear explanation for the effects has been developed, but it is generally considered that defects could play some role in the manifestation of these effects.…”