Computational Design of Long-Lifetime Room-Temperature Skyrmions

Magnetic skyrmions are spin textures that can serve as the key components in future logic devices. To retain information, long-term stability of the skyrmions at room temperature is necessary. Atomistic simulations have been developed to help identify the desirable skyrmionic materials [1-3]. We calculate the lifetimes of skyrmions at room temperature. To evaluate the activation energy for a collapsing skyrmion, the geodesic nudged elastic band (GNEB) method is employed. Additionally, the lifetime prefactor is obtained by using the harmonic approximation to the transition-state theory (HTST). Using these methods, skyrmions, with at least a year-long lifetime, are predicted in a 10 nm thick amorphous ferrimagnetic CoGd film. Additionally, we investigate the mechanism of skyrmion collapse along different reaction paths in the energy landscape. Furthermore, using machine learning, we explore several tunable parameters, including thickness, saturation magnetization, and Dzyaloshinskii-Moriya interactions (DMI), to optimize a heterostructure to host long-life room-temperature skyrmions.

[1] P. F. Bessarab et al., Phys. Rev. B 85, 184409 (2012).

[2] P. F. Bessarab et al., Comput. Phys. Commun 196, 335-347 (2015).

[3] M. Hoffmann et al., Phy. Rev. Lett. 124, 247201 (2020).