Gyroscopic dynamics of antiferromagnetic vortices in domain boundaries of yttrium orthoferrite

It is established experimentally that the magnetic field directed along the $b$ axis has little effect on the velocities of antiferromagnetic vortices in the domain boundary (DB) of yttrium orthoferrite and fails to explain the presence of an appreciable gyroscopic force acting on these vortices. This force is induced by the dynamic canting of magnetic sublattices proportional to the DB velocity. Due to the canting, the velocities of antiferromagnetic vortices depend initially quadratically on the DB velocity, as was experimentally found in this work. The dynamics of antiferromagnetic vortices in the yttrium orthoferrite DBs is gyroscopic and quasi-relativistic, with the limiting velocity of $20$ km/s equal to the velocity of spin waves at the linear portion of their dispersion curve.