Moving magnetic domain walls with sound alone

Area of Science:

• Spintronics
• Acoustics
• Materials Science

Background:

• Surface Acoustic Waves (SAW) are utilized in spintronics to reduce magnetic field or electric current requirements for magnetization control.
• A prevailing notion is that SAWs alone cannot achieve directed magnetic switching without auxiliary magnetic fields or currents.

Purpose of the Study:

• To demonstrate magnetic domain wall motion driven exclusively by acoustic waves.
• To investigate the mechanism of SAW-induced magnetic domain wall motion.
• To explore the potential for field-free spintronic device operation.

Main Methods:

• Utilizing X-ray Magnetic Circular Dichroism Photo Emission Electron Microscopy (XMCD-PEEM) for experimental observation.
• Conducting micromagnetic simulations to elucidate the underlying physical mechanism.
• Measuring domain wall velocities under SAW influence.

Main Results:

• Extensive evidence of SAW-induced, field-free magnetic domain wall (DW) motion was observed, propagating in the direction of the acoustic wave.
• Micromagnetic simulations revealed that SAWs can transfer linear momentum to DWs, enabling motion.
• Experimentally, the maximum average DW velocity reached approximately 12 m/s, with simulations predicting up to 100 m/s.

Conclusions:

• A novel mechanism for controlling magnetic domain wall motion solely through acoustic waves has been demonstrated.
• This discovery challenges the conventional understanding of SAW applications in spintronics.
• The findings pave the way for developing advanced spintronic devices controlled exclusively by acoustic waves, offering new avenues for innovation.