Bottom-Up Synthesis of Metallic CoNi Nanoplatelets with Magnetic Vortex-Like Spin Configurations

Area of Science:

• Materials Science
• Nanotechnology
• Magnetism

Background:

• Magnetic nanoplatelets offer tunable magnetic properties, switching between high magnetization and stray-field-free vortex states.
• Controlling magnetic configurations is key for applications in data storage and spintronics.

Purpose of the Study:

• To synthesize uniform cobalt-nickel (CoNi) nanoplatelets.
• To investigate the formation and stability of magnetic vortex structures in these nanoplatelets.

Main Methods:

• Topotactic reduction of metal hydroxides using hydrogen plasma.
• Magnetometry to track the paramagnetic-to-ferromagnetic transition.
• Lorentz transmission electron microscopy and scanning transmission X-ray microscopy for structural and magnetic imaging.
• Micromagnetic simulations to analyze magnetic states.

Main Results:

• Uniform CoNi nanoplatelets were successfully synthesized.
• Magnetic vortex-like structures were confirmed in isolated nanoplatelets at room temperature.
• Micromagnetic simulations predicted stable vortex remanent states for nanoplatelets with diameters of 200 nm to 1 μm and thickness around 12 nm.
• Structural defects and thickness variations did not destabilize the magnetic vortex configurations.

Conclusions:

• CoNi nanoplatelets can be synthesized with controlled magnetic vortex states.
• These vortex states are robust against common structural imperfections.
• The findings support the potential of CoNi nanoplatelets for applications requiring tunable, stray-field-free magnetic behavior.