High temperature Néel skyrmions in simple ferromagnets.

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanotechnology

Background:

• Chiral non-collinear spin textures, like skyrmions, offer unique properties for technological applications.
• Existing skyrmions are often found in complex materials and limited temperature ranges.

Purpose of the Study:

• To demonstrate the formation of Néel-type skyrmions in simple ferromagnetic alloys.
• To achieve skyrmion stability over a wide temperature range, including above room temperature.

Main Methods:

• Imposing a strain gradient perpendicular to the sample plane via epitaxy with an Ir-Al underlayer.
• Utilizing simple ferromagnetic alloys (Co-Al, Co-Ni-Al).
• Direct observation of skyrmions using Lorentz transmission electron microscopy (LTEM) in freestanding membranes.
• Measuring strain gradients using X-ray diffraction (XRD).

Main Results:

• Formation of Néel-type skyrmions in Co-Al and Co-Ni-Al thin layers.
• Skyrmions observed over a wide temperature range up to ~773 K.
• Demonstrated stability of skyrmions at temperatures well above room temperature.

Conclusions:

• Strain gradient engineering enables skyrmion formation in simple ferromagnets.
• High-temperature stability of skyrmions is achievable, overcoming previous limitations.
• This work brings skyrmionic electronics closer to practical realization.