Multi-domain structures in spheroidal Co nanoparticles

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Understanding micromagnetic states in magnetic nanoparticles is crucial for developing advanced magnetic storage and spintronic devices.
• Cobalt nanoparticles, particularly hexagonal close-packed (hcp) and face-centered cubic (fcc) structures, exhibit complex magnetic behaviors influenced by size, shape, and crystal anisotropy.

Purpose of the Study:

• To investigate the micromagnetic state structures in spheroidal hcp cobalt nanoparticles.
• To determine the single-domain diameters as a function of particle aspect ratio.
• To analyze the vortex structure of domain walls in two- and three-domain configurations and their impact on remanent magnetization.

Main Methods:

• Numerical simulations were employed to model micromagnetic states in hcp cobalt nanoparticles with diameters ranging from 20 to 200 nm.
• Calculations included determining single-domain diameters based on aspect ratio and analyzing domain wall structures.
• Remanent magnetization was computed for various multi-domain states.

Main Results:

• The study identified complex vortex structures within domain walls of two- and three-domain micromagnetic configurations.
• Three-domain states were characterized as deformed two-vortex states, with two distinct types found in larger hcp cobalt particles.
• These distinct three-domain states possess similar total energies but differ in the magnetization direction of their vortex core.

Conclusions:

• The aspect ratio significantly influences the single-domain diameter of hcp cobalt nanoparticles.
• Three-domain states in cobalt nanoparticles are complex, deformed vortex structures with implications for magnetic properties.
• Calculated remanent magnetization provides insights into the magnetic behavior of these nanoparticles for potential applications.