Science Daily August 11, 2021
A team of researchers in the US (University of North Florida, University of Illinois, Arizona State University) has demonstrated a new electronic phenomenon they call “asymmetric ferroelectricity” in atomic layer superlattices constructed using three constituent phases, CaTiO3, SrTiO3 and BaTiO3. The stacking sequence of the atomic layers is found to control the symmetry of the high-temperature dielectric response. When a nanostructured asymmetric strain is programmed into the lattice via the stacking order, the natural symmetry at high temperatures is removed and a polarized sample is obtained in which the polarization increases as the temperature is lowered. In contrast to a ferroelectric characterized by a bistable ground state with two equal and opposite electronic polarizations, their experiments showed evidence of asymmetric ferroelectric correlations that set in when such a sample becomes hysteretic below a temperature. The finding may lead to tailored electronic properties for interesting technological applications…read more. TECHNICAL ARTICLE
Natural ferroelectricity and asymmetric ferroelectricity by design. Credit: Phys. Rev. B 104, 085103, 4 August 2021Â