  We predict a fast domain wall (DW) motion induced by a thermal gradient
across a nanoscopic ferromagnetic stripe of MnBi. The driving mechanism is an
exchange torque fueled by magnon accumulation at the DWs. Depending on the
thickness of the sample, both hot-to-cold and cold-to-hot DW motion directions
are possible. The finding unveils an energy efficient way to manipulate DWs as
an essential element in magnetic information processing such as racetrack
memory.
