  Future applications of antiferromagnets (AFs) in many spintronics devices
rely on the precise manipulation of domain walls. The conventional approach
using static magnetic fields is inefficient due to the low susceptibility of
AFs. Recently proposed electrical manipulation with spin-orbit torques is
restricted to metals with a specific crystal structure.
  Here we propose an alternative, broadly applicable approach: using asymmetric
magnetic field pulses to induce controlled ratchet motion of AF domain walls.
  The efficiency of this approach is based on three peculiarities of AF
dynamics. First, a time-dependent magnetic field couples with an AF order
parameter stronger than a static magnetic field, which leads to higher mobility
of the domain walls. Second, the rate of change of the magnetic field couples
with the spatial variation of the AF order parameter inside the domain and this
enables synchronous motion of multiple domain walls with the same structure.
Third, tailored asymmetric field pulses in combination with static friction can
prevent backward motion of domain walls and thus lead to the desired controlled
ratchet effect.
  The proposed use of an external field, rather than internal spin-orbit
torques, avoids any restrictions on size, conductivity, and crystal structure
of the AF material.
  We believe that our approach paves a way for the development of new AF-based
devices based on controlled motion of AF domain walls.
