Gaining new insight into the thermal collapse of magnetic skyrmions

Skyrmions are energy efficient whirls of magnetization, which behave similarly to tiny hurricanes. These quasiparticles have potential applications in noncentrosymmetric materials and memory storage, because their spiral orientation is metastable, they can be moved around a surface, and information can be encoded in them as bits. With such promising applications, understanding the stability and longevity of metastable skyrmions is crucial.

By studying the thermal collapse rate of skyrmions, researchers gained information on the longevity of these whirls. Skyrmions need low temperatures to resist collapsing and to act as efficient memory devices. Through determination of a skyrmions longevity, Derras-Chouk et al. could also identify the lifetime of any product that would use these particles.

“The most widely known appeal of skyrmions is how energy efficient they are to move around. Successfully implementing them in memory storage would lead to huge gains in efficiency,” author Amel Derras-Chouk said.

The authors used a deterministic model to determine the collapse rate of skyrmions. This model was based upon solution of the system of stochastic Landau-Lifshitz equations for up to 104 spins and agreed with numerical results obtained by other experiments.

“In comparison to the Monte Carlo simulations, this method is more realistic as it describes the actual dynamics of the system,” Derras-Chouk said.

To continue this research, the authors suggested use of a probabilistic technique or a phase space approach to find a path between energy minimums. They believe the next step is to explore systems using different energy terms or constrained in a way that is different to a periodic two-dimensional lattice.

Source: “Thermal collapse of a skyrmion,” by Amel Derras-Chouk, Eugene M. Chudnovsky, and Dmitry A. Garanin, Journal of Applied Physics (2019). The article can be accessed at https://doi.org/10.1063/1.5109728 .