Related Experiment Video
Updated: May 28, 2026
07:03
Measuring Magnetically-Tuned Ferroelectric Polarization in Liquid Crystals
Published on: August 15, 2018
Transient negative capacitance in ferroelectric and twist-bend ferroelectric nematic liquid crystals
Netra Prasad Dhakal1,2, Manisha Talwar1,3, Zakaria Siddiquee1,3
1Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, OH 44242, USA. ajakli@kent.edu.
Soft Matter
|May 27, 2026
Summary
Negative capacitance (NC) in ferroelectric liquid crystals is confirmed in fluid nematic and twist-bend nematic phases. This finding suggests NC is broadly applicable in ferroelectric nematic liquid crystals for reduced power dissipation.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Liquid Crystals
Background:
- Negative capacitance (NC) in ferroelectric materials offers a pathway to reduce power dissipation in electronic devices.
- Recent studies have demonstrated the existence of NC in fluid ferroelectric nematic (NF) liquid crystals.
- Understanding NC in liquid crystal systems is crucial for developing advanced electronic applications.
Purpose of the Study:
- To investigate the conditions under which negative capacitance (NC) exists in ferroelectric nematic liquid crystal materials.
- To explore the phenomenon of NC in a fluid twist-bend ferroelectric nematic liquid crystal (NTBF) phase.
- To analyze the polarization switching mechanisms and estimate rotational viscosities in the NTBF phase.
Main Methods:
- Experimental investigation of negative capacitance in ferroelectric nematic and twist-bend ferroelectric nematic liquid crystals.
- Application of square-wave voltage and analysis of polarization-voltage (P-V) hysteresis curves.
- Measurement and analysis of polarization switching dynamics and rotational viscosities.
Main Results:
- Negative capacitance (NC) is indicated to exist in all ferroelectric nematic liquid crystals when polarization switching time exceeds the applied voltage rise time.
- In the twist-bend ferroelectric nematic liquid crystal (NTBF) phase, polarization switching occurs in two distinct steps.
- Four negative capacitance ranges were observed in the P-V hysteresis curves of the NTBF phase, contrasting with two ranges in conventional ferroelectric crystals and NF materials.
Conclusions:
- Negative capacitance is a prevalent phenomenon in ferroelectric nematic liquid crystals under specific switching conditions.
- The twist-bend ferroelectric nematic liquid crystal phase exhibits unique multi-step polarization switching behavior leading to multiple NC ranges.
- The study provides insights into the physical mechanisms governing polarization switching and offers estimates for rotational viscosities in NTBF materials.
Related Concept Videos
01:31Dielectric Polarization in a Capacitor
The presence of a dielectric medium in a capacitor not only changes the voltage and capacitance but also affects the electric field. In general, dielectrics can be of two types: polar and nonpolar. In a polar dielectric, the positive and negative charges in the molecules are separated by a distance and hence have a permanent dipole moment. In contrast, no such charge separation exists in a nonpolar dielectric, however the nonpolar molecules get polarized in the presence of an external electric...
01:25MOS Capacitor
A Metal-Oxide-Semiconductor (MOS) capacitor is a fundamental structure used extensively in semiconductor device technology, particularly in the fabrication of integrated circuits and MOSFETs (metal-oxide-semiconductor field-effect transistors). The MOS capacitor consists of three layers: a metal gate, a dielectric oxide, and a semiconductor substrate.
The metal gate is typically made from highly conductive materials such as aluminum or polysilicon. Beneath the metal gate lies a thin layer of...
The metal gate is typically made from highly conductive materials such as aluminum or polysilicon. Beneath the metal gate lies a thin layer of...
01:26Susceptibility, Permittivity and Dielectric Constant
When placed in an external electric field, a dielectric material gets polarized. The charge density in the dielectric material is given by the sum of the bound and free charge densities, while the total charge density can also be written in terms of the total electric field. The bound charge density can be measured in terms of polarization, leading to the relationship between electric displacement and polarization.
01:11P-N junction
A p-n junction is formed when p-type and n-type semiconductor materials are joined together. At the interface of the p-n junction, holes from the p-side and electrons from the n-side begin to diffuse into the opposite sides due to the concentration gradient. This diffusion of carriers leads to a region around the junction where there are no free charge carriers, known as the depletion region. The charge density within the depletion region for the n-side and p-side can be described by the...
01:29Potential Due to a Polarized Object
A neutral atom consists of a positively charged nucleus surrounded by a negatively charged electron cloud. When placed in an external electric field, the external electric force pulls the electrons and nucleus apart, opposite to the intrinsic attraction between the nucleus and the electrons. The opposing forces balance each other with a slight shift between the center of masses of the nucleus and the electron cloud, resulting in a polarized atom. On the other hand, a few molecules, like water,...
01:26Imperfections in Crystal Structure: Stoichiometric Point Defects
Schottky defects arise when some lattice points in a crystal, such as those in NaCl, remain unoccupied, creating lattice vacancies without disturbing the overall electrical neutrality of the crystal. This defect is common in ionic crystals where the positive and negative ions are similar in size, as seen in sodium chloride and cesium chloride. The presence of Schottky defects enables the crystal to conduct electricity to a small extent through an ionic mechanism. Electric fields cause nearby...