Unconventional ferroelectric domain switching dynamics in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>CuIn</mml:mi><mml:msub><mml:mi mathvariant="normal">P</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi mathvariant="normal">S</mml:mi><mml:mn>6</mml:mn></mml:msub></mml:mrow></mml:math> from first principles
Ri He, Hua Wang, Fucai Liu, Shi Liu, Houfang Liu, Zhicheng Zhong
Abstract
The switching dynamics of ferroelectric materials is a crucial intrinsic property which directly affects the operation and performance of ferroelectric devices. In conventional ferroelectric materials, the typical ferroelectric switching mechanism is governed by a universal process of domain-wall motion. However, recent experiments indicate that van der Waals ferroelectric $\mathrm{CuIn}{\mathrm{P}}_{2}{\mathrm{S}}_{6}$ possesses anomalous polarization switching dynamics under an electric field. It is important to understand the switching dynamics, but it remains theoretically unexplored in $\mathrm{CuIn}{\mathrm{P}}_{2}{\mathrm{S}}_{6}$ due to the lack of description of its order-disorder phase transition characteristics by density functional theory. Here we employ a machine-learning potential trained from the first-principles density functional theory dataset to conduct large-scale atomistic simulations of temperature-driven order-disorder ferroelectric phase transition in $\mathrm{CuIn}{\mathrm{P}}_{2}{\mathrm{S}}_{6}$. Most importantly, it is found that the electric-field-driven polarization switching in $\mathrm{CuIn}{\mathrm{P}}_{2}{\mathrm{S}}_{6}$ is mediated by a single Cu dipole flip rather than a conventional domain-wall-motion mechanism. This intrinsic unconventional switching behavior can be attributed to the competition between the energy barrier of domain-wall motion and single-dipole flip.