Dynamics of interstitial skyrmions in the presence of temperature gradients

An interstitial skyrmion is the skyrmion state confined in the helical background. While the spin helix naturally provides the one-dimensional channels in helical magnets, the dynamics of an interstitial skyrmion are different from that for free skyrmions in a ferromagnetic or conical background. In this paper, we studied the dynamics of interstitial skyrmions under a temperature gradient numerically and analytically. We show that the interstitial skyrmion moves from the hot area to the cold area in the presence of temperature gradients, in contrast to skyrmions in the ferromagnetic background, where they move towards the hot region. Because the interstitial skyrmion is confined in the one-dimensional channel, it moves in the same direction as the magnon flow induced by the temperature gradient, where the $\ensuremath{\beta}$-type thermomagnonic torque plays an essential role.