Marble game with optimal ferroelectric switching

Abstract

A low coercivity and, consequently, low hysteresis loss are desired properties for ferroelectric materials used in high-power and high-frequency actuators. The coercive field required for the onset of ferroelectric switching is shown to develop a strong directional anisotropy due to peculiarities of an energy surface associated with the polarization rotation. It is found that the ferroelectric anisotropy exhibits 'hard' and 'easy' switching axes similar to magnetic materials. The hard axis corresponds to 180° polarization reversal, whereas the easy axis favors 90° switching. Our results suggest that the intrinsic low coercivity and the full polarization reversal may not be achieved at the same time under uniaxial excitation. A rotating electric field excitation is proposed in order to circumvent this limitation and to guide the polarization switching along a curved path.

Suppressing the ferroelectric switching barrier in hybrid improper ferroelectrics

“…. Though these coercive fields are comparable to values suitable for integration to silicon chips (E c ≈ 50 kV cm −1 ), applications such as high-power actuators and low-voltage logic and memory elements ask for ferroelectrics with robust polarizations that can be switched by a lower coercive field [12][13][14][15] . Ultra-low coercive fields as low as 5 kV cm −1 were observed in pulsed laser deposition grown Ca 3 Ti 2 O 7 thin films, but the reason behind this reduction (and whether it is an intrinsic or an extrinsic effect) is not clarified yet 16 .…”

Efficient Driving of Piezoelectric Transducers Using a Biaxial Driving Technique

“…These measurements are in agreement with our previous numerical studies that predicted this phenomenon. Furthermore, the predictions in [ 3 ] indicated that the coercive field is highly anisotropic, and it was anticipated that the ferroelectric hysteresis would be sensitive to the direction of the applied electric field. The first principles modelling used in [ 1 – 3 ] differs from most macroscopic phenomenological modelling since the total energy losses in the former model are linked to the coercive field that opposes the external electric field.…”

“…Furthermore, the predictions in [ 3 ] indicated that the coercive field is highly anisotropic, and it was anticipated that the ferroelectric hysteresis would be sensitive to the direction of the applied electric field. The first principles modelling used in [ 1 – 3 ] differs from most macroscopic phenomenological modelling since the total energy losses in the former model are linked to the coercive field that opposes the external electric field. For the macriscopic phenomenological approach, the mechanical losses and the electric losses are often approximated separately and have been of great value in characterizing the losses of resonant or non-resonant driving of piezoelectric actuators [ 7 , 9 ].…”

“…Piezoelectric actuators are commonly driven by applying the electric field along the poling axis in order to maximize their mechanical response. To better understand the piezoelectricity phenomenon, and evaluate potential solutions to increase efficiency, our group has performed preliminary microscopic theoretical studies using modern polarization theory to establish a relation between atomic structure and dielectric dissipation of ferroelectric materials [ 1 – 3 ]. In this preliminary work, we adapted Density Functional Theory [ 4 , 5 ] to better understand the energetics of ferroelectric switching driven by an external electric field.…”

“…A possible strategy to facilitate polarization rotation along a curved path uses two-dimensional excitation with active modulation of the E x ( t ) and E z ( t ) components of the applied field. Our work in [ 3 ] suggested that the application of two orthogonal electric fields, instead of one as commonly done in most applications, can significantly reduce the coercivity that opposes the ferroelectric switching. A specific condition was predicted whereby a rotating electric field would result in a reduction in the coercivity.…”