Related Experiment Video
Updated: Jul 30, 2025
06:26
Orientational Transition in a Liquid Crystal Triggered by the Thermodynamic Growth of Interfacial Wetting Sheets
Published on: May 15, 2017
7.2K
Sliding Phase Transition in Ferroelectric van der Waals Bilayers
Ping Tang1, Gerrit E W Bauer1,2,3,4
1WPI-AIMR, Tohoku University, 2-1-1 Katahira, Sendai 980-8577, Japan.
Physical Review Letters
|May 12, 2023
Summary
This study explains the stable ferroelectricity in van der Waals bilayers like hexagonal boron nitride (h-BN) and tungsten disulfide (WTe2) due to their strong in-plane stiffness. Researchers calculated key properties to compare with experimental observations.
Area of Science:
- Condensed matter physics
- Materials science
- Nanotechnology
Background:
- Van der Waals (vdW) bonded bilayers exhibit unique electronic properties.
- Ferroelectricity has been recently observed in hexagonal boron nitride (h-BN) and tungsten disulfide (WTe2) bilayers.
- Understanding the factors governing ferroelectric robustness is crucial for device applications.
Purpose of the Study:
- To investigate the sliding thermodynamics of vdW-bonded bilayers using continuum electromechanics.
- To attribute the observed ferroelectric robustness in h-BN and WTe2 bilayers to the in-plane stiffness of monolayers.
- To compute electric susceptibility and specific heat and compare critical temperatures and electric switching fields with experimental values.
Main Methods:
- Continuum electromechanics modeling.
- Mean-field self-consistent phonon approximation.
- Thermodynamic calculations of sliding bilayers.
Main Results:
- The in-plane stiffness of monolayers is identified as the key factor for robust ferroelectricity in h-BN and WTe2 bilayers.
- Electric susceptibility and specific heat were computed.
- Calculated critical temperatures and electric switching fields show good agreement with experimental data.
Conclusions:
- The in-plane stiffness of constituent monolayers is critical for robust ferroelectricity in vdW bilayers.
- Continuum electromechanics provides a valid framework for studying sliding thermodynamics in these systems.
- The findings offer insights into the design and optimization of ferroelectric vdW heterostructures.
Related Concept Videos
02:39Phase Transitions: Melting and Freezing
12.5K
Heating a crystalline solid increases the average energy of its atoms, molecules, or ions, and the solid gets hotter. At some point, the added energy becomes large enough to partially overcome the forces holding the molecules or ions of the solid in their fixed positions, and the solid begins the process of transitioning to the liquid state or melting. At this point, the temperature of the solid stops rising, despite the continual input of heat, and it remains constant until all of the solid is...
12.5K
02:33Phase Transitions: Sublimation and Deposition
17.3K
Some solids can transition directly into the gaseous state, bypassing the liquid state, via a process known as sublimation. At room temperature and standard pressure, a piece of dry ice (solid CO2) sublimes, appearing to gradually disappear without ever forming any liquid. Snow and ice sublimate at temperatures below the melting point of water, a slow process that may be accelerated by winds and the reduced atmospheric pressures at high altitudes. When solid iodine is warmed, the solid sublimes...
17.3K
02:31Phase Transitions
19.3K
Whether solid, liquid, or gas, a substance's state depends on the order and arrangement of its particles (atoms, molecules, or ions). Particles in the solid pack closely together, generally in a pattern. The particles vibrate about their fixed positions but do not move or squeeze past their neighbors. In liquids, although the particles are closely spaced, they are randomly arranged. The position of the particles are not fixed—that is, they are free to move past their neighbors to...
19.3K
01:31Dielectric Polarization in a Capacitor
4.8K
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...
4.8K
01:19Phase Diagram
6.0K
The phase of a given substance depends on the pressure and temperature. Thus, plots of pressure versus temperature showing the phase in each region provide considerable insights into the thermal properties of substances. Such plots are known as phase diagrams. For instance, in the phase diagram for water (Figure 1), the solid curve boundaries between the phases indicate phase transitions (i.e., temperatures and pressures at which the phases coexist).
6.0K
02:39Phase Transitions: Vaporization and Condensation
17.7K
The physical form of a substance changes on changing its temperature. For example, raising the temperature of a liquid causes the liquid to vaporize (convert into vapor). The process is called vaporization—a surface phenomenon. Vaporization occurs when the thermal motion of the molecules overcome the intermolecular forces, and the molecules (at the surface) escape into the gaseous state. When a liquid vaporizes in a closed container, gas molecules cannot escape. As these gas phase...
17.7K