Extended Data Fig. 3: Jx−tp threshold conditions for skyrmion depinning (blue circles), heat dominated motion (red triangles), and random nucleation and annihilation of skyrmion bubbles in TmIG (black squares).
From: Current-driven dynamics and ratchet effect of skyrmion bubbles in a ferrimagnetic insulator
\(|H_z| = 20\) Oe and the YIG layer is demagnetized. No difference was observed between \(Q = + 1\) and \(- 1\) skyrmion bubbles. Supplementary Note 9 presents the current threshold for skyrmion depinning in the presence of \({{{\mathbf{H}}}}_y\), that is, with \({{{\mathbf{M}}}}_{{{{\mathrm{YIG}}}}}\) controlled with an in-plane magnetic field. All measurements of the skyrmion dynamics presented in this work were performed for \(t_{{{\mathrm{p}}}},\left| {J_x} \right|\) conditions comprised between the curves defined by the blue circles and the red triangles. Above the threshold defined by the red triangles, the mean displacements \(\overline {\Delta x} ,\overline {\Delta y}\) abruptly drop, indicating that the skyrmion dynamics are dominated by Joule heating induced random skyrmion motion rather than by SOTs. We attribute this behavior to the exponential increase of the skyrmion diffusivity with temperature, which is expected in materials with low disorder and low damping such as TmIG9.
