New Submission Ferroelectric switching pathways in BaTiO₃ under uniaxial strain from first principles

Recent advances in freestanding oxide membrane synthesis have revealed new methods to enhance ferroelectric performance, including faster switching times and reduced switching energies compared to substrate-constrained thin films. Within these membranes, uniaxial strain can be applied along different crystallographic axes, facilitating the creation of unique strain states with different strain amplitudes along different axes. Understanding the phase energetics under uniaxial strain is crucial for elucidating ferroelectric switching pathways in these membranes. Although the effect of biaxial strain on BaTiO₃ has been extensively studied, the impact of uniaxial strain on ferroelectric switching pathways remains less explored. Here, we employ first-principles density functional theory calculations to investigate the influence of uniaxial strain along the [100], [110] and [111] crystallographic directions on the phase stability and ferroelectric switching pathways of BaTiO₃. Under uniaxial strain along [100], we find that the rhombohedral phase remains the ground state at moderate strains, transitioning to orthorhombic or tetragonal phases under compressive or tensile strains, respectively. Similar phase transitions occur under [110] strain. We analyze the ferroelectric switching pathways by examining energy landscapes and identify pathways with low energy barriers that pass through intermediate low-energy polar phases. These findings provide insight into tuning ferroelectric properties and designing low-energy switching pathways in BaTiO3, potentially guiding the development of next-generation low-power devices utilizing freestanding ferroelectric oxide membranes.