Extended Data Fig. 8: Micromagnetic simulation results of the diffusion of skyrmions purely driven by temperature gradients.

The micromagnetic simulation of skyrmion diffusion in a nanowire geometry is performed by using the open boundary condition. First, skyrmions are thermally generated at high temperature side using a larger temperature gradient. Subsequently, the temperature gradient is reduced to avoid the nucleation of skyrmions at the hot side, which results in the diffusion of skyrmions towards the cold side. Some skyrmions exit the nanowire through the sample edge during the diffusion. The length and width of the nanowire are 120J_ex/D and 40J_ex/D, respectively. The thermal gradient for diffusion is k = 0.008J_ex/k_B. Disorders in spin anisotropy are introduced to suppress the magnonic spin torque by reducing the magnon mean free path. Here we assume the film thickness is 0.1J_ex/D. The scale bar is 10J_ex/D.