Slide and twist: manipulating polarization in multilayer hexagonal boron-nitride

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Ferroelectricity in layered materials offers potential for novel electronic devices.
• Controlling out-of-plane polarization in hexagonal boron nitride (hBN) multilayers is crucial for device applications.
• Understanding the energy landscape of layer sliding is key to manipulating polarization.

Purpose of the Study:

• To investigate across-layer sliding ferroelectricity in multilayer hexagonal boron nitride (hBN).
• To identify viable methods for controlling and reversing out-of-plane polarization.
• To explore the impact of stacking configurations and layer rotations on polarization behavior.

Main Methods:

• Simulations of sliding single or dual layers in various hBN stacking configurations.
• Calculation of energy barriers for polarization reversal.
• Analysis of polarization stability during sliding.
• Investigation of rotated multilayer structures and their polarization characteristics.

Main Results:

• Identified experimentally viable methods for polarization reversal with energy barriers of 5-30 meV per formula unit (f.u.).
• Found single-interface sliding to be more energetically favorable than multiple-interface sliding.
• Observed stable polarization plateaus during specific sliding pathways.
• Demonstrated consistent net out-of-plane polarization in rotated multilayer structures.
• Showcased polarization reversal in trilayer ABT structures via combined rotation and sliding.

Conclusions:

• Across-layer sliding provides a feasible route for controlling ferroelectricity in multilayer hBN.
• The identified low energy barriers support the fabrication of devices based on these multilayer structures.
• Similar phenomena in hexagonal gallium nitride (hGaN) suggest broader applicability in polar materials.