Geometry-induced spin chirality in a non-chiral ferromagnet at zero field.

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanotechnology

Background:

• Spin chirality is key to magnetochiral anisotropy (MChA), enabling non-reciprocal transport.
• Current MChA applications are limited by external magnetic fields, complex synthesis, and cryogenic conditions.

Purpose of the Study:

• To develop a scalable nanotechnology for imprinting spin chirality onto non-chiral materials.
• To achieve spontaneous MChA and non-reciprocal transport at room temperature and zero magnetic field.

Main Methods:

• Three-dimensional nanoengineering using two-photon lithography to create a twisted polymeric template.
• Coating the template with a uniform 30-nm-thick nickel shell.
• Characterization using X-ray magnetic circular dichroism microscopy and inelastic light scattering spectroscopy.

Main Results:

• The chiral nickel tube exhibited spontaneous MChA and non-reciprocal transport at zero magnetic field and room temperature.
• Helical spin textures were stabilized by engineered shape anisotropy, confirmed by X-ray microscopy.
• Robust non-reciprocal magnon transport was demonstrated, reconfigurable by magnetic field history.

Conclusions:

• Geometric chirality can be imprinted onto non-chiral ferromagnets, overcoming limitations of traditional MChA.
• The developed nanotechnology is scalable and enhances chiral magnonics and spintronics for practical applications.
• Downscaling feature sizes further boosts non-reciprocity, surpassing natural chiral magnets.