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Interplay of domain structure, phase transitions and functional responses in ferroelectric (Ba,Sr)TiO3
- Date: 31.05.2023
- Place: Symposium: Materials for energy conversion systems: fundamentals, designs, and applications at the EMRS Fall Meeting, Strasbourg, France
Domain walls and phase boundaries are fundamental ingredients of ferroelectrics and govern their functional properties important for applications ranging from frequency conversion, energy harvesting, electrocaloric cooling and piezoelectric actuation to data storage. Although both interfaces have been studied for decades, often only a phenomenological macroscopic understanding has been established and recent studies reveal unexpected microscopic properties .
In this contribution we combine density functional theory and molecular dynamics simulations to study the microscopic processes governing the field-induced domain wall motion in (Sr,Ba)TiO3 as well as the impact of domain walls on the tetragonal to orthorhombic phase transition . Excitingly, we find that fast field changes may boost the wall velocity by non- equilibrium switching of local dipoles . With time these dipoles switch back and the domain wall motion reaches its steady state. On the other hand, the dynamics of walls can be considerably modified by point defects and inhomogeneities. For example, Sr-rich regions strained by a surrounding Ba-rich matrix increase the energy barrier for the wall motion and my act as pinning centers for domain walls .
In the orthorhombic phase, local non-180o switching of dipoles on the traveling walls results in transient local Bloch type walls and dipole vortices.
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