Stability and deterministic switching of polar vortices and skyrmions
In plain words
In thin layered oxide films, electric dipoles can curl into vortices and skyrmions (stable swirling patterns) a few dozen atoms wide. Why they are stable, and how much field, energy and time it takes to write or erase a single one, is open.
Precise statement
In $(\mathrm{PbTiO3})_{n}/(\mathrm{SrTiO3})_{n}$ superlattices with $n \sim 10\ \text{to}\ 16$, polar vortex arrays (Yadav et al., Nature 2016) and room-temperature polar skyrmions (Das et al., Nature 2019) form from competition of elastic, electrostatic and gradient energies. Determine the phase diagram in $(n,\ \mathrm{strain},\ T,\ E)$, the energy barrier protecting an isolated skyrmion, and the threshold field, energy and time for deterministic creation and erasure of a single topologically characterized skyrmion. An answer is computed phase boundaries and barriers confirmed by single-texture switching experiments.
What would settle it
Repeatable creation and erasure of a single polar skyrmion by a scanning-probe field pulse with measured threshold, compared with a first-principles-based barrier calculation.
Status in the literature
Unverified note
Local field switching of skyrmion-like polar nanodomains was reported in 2022 (Han et al., Nature); the barrier of an isolated skyrmion and its switching energy and time had not been determined as of 2025.