Magnetic field control of antiferromagnetic domain walls in a thermal gradient

An antiferromagnetic domain wall in a thermal gradient is found to experience a force towards colder regions upon the application of a uniform magnetic field along the easy axis. This force increases with the strength of the applied field and, for sufficiently high values, it overcomes the entropic force that pushes the wall towards the hotter regions. The force is proportional to the thermal gradient and it shows a linear dependence with the net magnetic moment of the domain wall induced by the field. The origin of this force lies in the increase of the domain wall reflectivity due the field-induced sizable break of the antiferromagnetic order inside it. Thus, reflected magnons effectively transfer linear momentum to the domain wall and push it to the cold regions.