Moiré magnetic exchange interactions in twisted magnets

Area of Science:

• Condensed Matter Physics
• Materials Science
• Spintronics

Background:

• Twisting van der Waals materials creates moiré superlattices with novel electronic and magnetic properties.
• Moiré magnetic exchange interactions (MMEIs) arise from twisting but are poorly understood due to model limitations.

Purpose of the Study:

• To develop a microscopic model for MMEIs in twisted magnets.
• To investigate MMEI-induced spin textures and their control.

Main Methods:

• Development of a microscopic moiré spin Hamiltonian using a sliding-mapping approach.
• Theoretical modeling applied to twisted bilayer CrI₃.

Main Results:

• The model effectively describes MMEIs, revealing their twist-angle dependence.
• Discovery of 'moiré-type skyrmion bubbles'—unique spin textures generated by MMEIs.
• Demonstration of twist-angle control over skyrmion bubble size and population.

Conclusions:

• MMEIs are crucial for understanding magnetism in twisted van der Waals materials.
• Moiré-type skyrmion bubbles offer a new platform for spintronic devices, particularly for information storage.
• MMEIs can be tuned by substrate interactions, reconciling theoretical predictions with experimental observations.