Thermal motion of skyrmion arrays in granular films

Weakly pinned skyrmion liquid in a magnetic heterostructure

“…The simulation includes a grain structure of 10 nm average diameter with a corresponding variation in the magnetic anisotropy (as a Gaussian distribution with a standard deviation of 5%) and DMI (as a Gaussian distribution with a standard deviation of 15%). The skyrmions are both thermally excited into motion and interact with the grains [19]. Although similar material parameters are used as in the experiments, the skyrmions in the simulations are significantly smaller, with an average radius around 14 nm, and the relevant timescales are orders of magnitude shorter.…”

“…However, Eq. ( 2) only applies to an isolated single skyrmion on a smooth film, and the skyrmion behavior is likely to be modified in the presence of an interacting array of skyrmions, as well as in the presence of pinning sites [19].…”

“…The implementation of skyrmion diffusion-based devices in ultrathin films will require an indepth understanding of the interaction between skyrmions and the material grains and pinning sites commonly found in such films [15][16][17]. The interaction of skyrmions with such defects has so far been studied using molecular dynamic and micromagnetic simulations [18,19], as well as through the combination of experimental and simulation work [20,21].…”

Chiral Skyrmions Interacting with Chiral Flowers

“…34−58 For example, a skyrmion driven by the spin−orbit torques may show the skyrmion Hall effect, 39,42,59,60 where the skyrmion moves at an angle with respect to the applied current direction. On the other hand, a skyrmion driven by thermal effects may show the Brownian gyromotion, [36][37][38]40,41,43,[47][48][49][50]56 where the skyrmion tends to move in circular trajectories during the random walk. Skyrmions can also be driven into directional motion by thermal gradients.…”

“…14,24,[61][62][63][64][65]68 In 2013, Mijalkov and Volpe demonstrated the possibility that particle-like chiral microswimmers performing circular active Brownian motion can be sorted in a chiral environment formed by using some static obstacle patterns on the substrate, 69,70 where the chirality of circular Brownian motion couples to chiral features present in the environment. As skyrmions also show circular Brownian motion due to their nontrivial topology, [36][37][38]40,41,43,[47][48][49][50]56 it is therefore envisioned that the thermally activated random-walk dynamics of skyrmions may also be modified in a chiral environment due to the skyrmion−substrate interactions, which is the focus of this work. However, it should be noted that active matter systems have some form of self-propulsion, 66,67,69,70 while the Brownian skyrmions are only undergoing thermal motion and are not self-propelled.…”