Spin-Wave Emission from Vortex Cores under Static Magnetic Bias Fields

Area of Science:

• Condensed matter physics
• Materials science
• Nanotechnology

Background:

• Spin waves are fundamental excitations in magnetic materials.
• Magnetic vortex cores are promising for nanoscale spin-wave devices.
• Controlling spin-wave emission is crucial for spintronic applications.

Purpose of the Study:

• Investigate the effect of static magnetic fields on spin-wave emission from magnetic vortex cores.
• Understand how magnetic bias fields influence spin-wave propagation characteristics.
• Explore potential focusing effects in spin-wave emission.

Main Methods:

• Time-resolved scanning transmission X-ray microscopy (TR-STXM) for imaging spin waves.
• Utilized disk structures of synthetic ferrimagnets and single ferromagnetic layers.
• Employed micromagnetic simulations to corroborate experimental findings.

Main Results:

• Static magnetic bias fields continuously displace the vortex core from the disk center to the edge.
• Spin-wave dispersion relations remain largely unaffected by the magnetic bias field.
• Anisotropic core expansion in single-layer disks leads to directional spin-wave emission and propagation.
• Micromagnetic simulations reveal field-controlled focusing effects.

Conclusions:

• Static magnetic fields offer a method to control the location and directionality of spin-wave emission from vortex cores.
• The findings are relevant for designing advanced spintronic devices.
• Focusing effects can be tuned by magnetic fields, opening possibilities for wave manipulation.