Geometrically driven chiral effects in curvilinear antiferromagnetic spin chains

Antiferromagnets are technologically promising materials for spintronic and spinorbirtonic devices [1]. An efficient manipulation of antiferromagnetic textures requires the presence of the Dzyaloshinskii-Moriya interaction (DMI), which is present in crystals of special symmetry, and thus limits the number of available materials. In contrast to antiferromagnets, it is already established that in ferromagnetic thin films and nanowires chiral responses can be tailored relying on curvilinear geometries [2].

Here, we explore curvature effects in curvilinear antiferromagnets [3]. We demonstrate theoretically that intrinsically achiral curvilinear antiferromagnetic spin chains behave as a biaxial chiral helimagnet with a curvature-tunable anisotropy and DMI. In contrast to ferromagnetic spin chains, this system possesses the hard-axis anisotropy stemming from the dipolar interaction, which allows to observe the effects of geometry even in chains with small curvature and torsion. The geometry-driven easy axis anisotropy determines the homogeneous antiferromagnetic state at low curvatures and the gap for spin waves. The geometry-driven DMI determines the helimagnetic phase transition and leads to the appearance of the region with the negative group velocity at the dispersion curve.

[1] V. Baltz et al., Rev. Mod. Phys. 90, 015005 (2018)
[2] R. Streubel et al., J. Phys. D.: Appl. Phys. 49, 363001 (2016)
[3] O. V. Pylypovskyi, D. Y. Kononenko et al., Nano Lett. 20, 8157 (2020)