Abstract
The manipulation of a ferroelectric vortex under the boundary condition of inhomogeneous screening is simulated by phase-field calculations. It is revealed that the vortex chirality can be tuned by utilizing uniform electric fields under inhomogeneous screening boundary conditions in which the switching mechanism is distinct from that under boundary conditions of asymmetric screening previously reported. The influence of the screening inhomogeneity and the ambient temperature on the vortex switching is further studied. The results indicate that inhomogeneous screening conditions are of vital importance to the switching behaviors of vortex chirality in a ferroelectric nanodot under the influence of a uniform electric field. Furthermore, the critical electric field is inextricably linked to the screening inhomogeneity and the ambient temperature.
Highlights
INTRODUCTIONA vortex is a typical topological structure in ferroic materials. Due to its promising application prospects in sensors, actuators, non-volatile memories, etc., the vortex and its manipulation have been drawing increasing attention in recent years. Distinct from a ferromagnetic vortex, a ferroelectric vortex is a representative two-dimensional topological domain structure wherein all polarization whirls to form a closed-loop morphology and no polarization are present in the core region
Identical to the significance of the asymmetric electrical boundary conditions on the vortex switching by breaking the symmetry of the stabilized vortex domain structure, the inhomogeneous surface screening situations should not be ignored and can play an important role in vortex control
Regarding the external electrical field as the main controlling factor and other interfering factors, i.e., boundary conditions and ambient temperature, as the adjustable parameters, we employed inhomogeneous screening conditions on the surface to study the effect on the switching behaviors of the vortex chirality
Summary
A vortex is a typical topological structure in ferroic materials. Due to its promising application prospects in sensors, actuators, non-volatile memories, etc., the vortex and its manipulation have been drawing increasing attention in recent years. Distinct from a ferromagnetic vortex, a ferroelectric vortex is a representative two-dimensional topological domain structure wherein all polarization whirls to form a closed-loop morphology and no polarization are present in the core region.. Under near open-circuit (OC) conditions, the depolarization fields drive electric dipoles to redistribute in a head-to-tail style into a closed configuration with definite chirality.7 It was initially predicted by effective Hamiltonian calculations that ferroelectric vortex domains exist in nanoscale structures.. Strategies to induce asymmetric factors, including geometric structures with different concavity and convexity, and compositional gradient materials, have been proposed to achieve chirality reversal of a vortex by homogeneous electric fields. The surface screening condition that determines the depolarization field performs a prominent part during the process of chirality manipulation of the vortex domain structure. We have proposed the feasibility of vortex switching in asymmetric screening conditions and investigated the process of chirality reversal of a vortex by uniform electric fields.. Investigate the effect of inhomogeneous screening on the feasibility of achieving the switching behaviors of a vortex induced by uniform electric fields
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