Exchange Surface Spin Waves in Type-A van der Waals Antiferromagnets

Area of Science:

• Condensed matter physics
• Materials science
• Quantum magnetism

Background:

• Surface waves are crucial in various scientific fields.
• Van der Waals (vdW) magnets offer unique magnetic properties.
• Antiferromagnets are key components in spintronic applications.

Purpose of the Study:

• To predict and characterize novel surface spin wave excitations in vdW antiferromagnets.
• To explore their potential for nanoscale magnonic devices.
• To investigate their excitation mechanisms and observable properties.

Main Methods:

• Theoretical prediction of surface spin waves.
• Analysis of bulk magnon band gaps in type-A vdW antiferromagnets.
• Investigation of exchange modes and their persistence.
• Simulation of electromagnetic wave excitation and absorption.
• Analysis of emitted magnetic stray fields.

Main Results:

• Discovery of nanoscale-confined surface spin waves in vdW antiferromagnets.
• These waves are pure exchange modes, distinct from conventional magnetostatic modes.
• Efficient excitation by electromagnetic waves with significant absorption.
• Observation of even-odd oscillations in magnetic stray fields with monolayer number.

Conclusions:

• vdW antiferromagnets host unique surface spin waves with potential for ultrafast, nanoscale magnonic devices.
• These spin waves are robust, persisting in ultrathin stacks and at large wave numbers.
• The predicted magnetic stray field oscillations are experimentally verifiable using nitrogen-vacancy-center magnetometry.