Strain-Engineered Phase Diagrams in (SrTiO3)8/(BaTiO3)8 Superlattices: Toward Néel Skyrmions and Energy Storage

Misfit strain between the substrate and the superlattice plays a critical role in determining the domain configurations and ferroelectric properties of superlattice heterostructures. This implies that a proper substrate material can be selected to design and tailor the domain structure and the properties of the superlattice. However, the influence of the substrate-induced strain on domain structures and polarization switching processes under different substrates is difficult to observe experimentally. In this study, we employ the phase-field method to explore the effects of different substrates on the domain patterns and switching properties of superlattice heterostructures. A phase diagram mapping substrate lattice parameters against the electric field was constructed for ferroelectric (SrTiO3)8/(BaTiO3)8 superlattice thin films. Néel-type skyrmion structures were observed under an applied electric field and could be stabilized upon field removal. Two distinct switching modes were also identified, depending on the substrate. Additionally, we observed that misfit strain-induced hysteresis linearization enhances both recoverable energy density and energy storage efficiency, suggesting that superlattice heterostructures hold promise for energy storage applications. Our findings provide new insights into the switching mechanisms of superlattice structures and pave the way for designing next-generation functional nanoelectronic devices.