  In this work, we study the antiferromagnetic (AFM) spin dynamics in
heterostructures which consist of two kinds of AFM layers. Our micromagnetic
simulations demonstrate that the AFM domain-wall (DW) can be driven by the
other one (driven by field-like Neel spin-orbit torque, Phys. Rev. Lett. 117,
017202 (2016)) through the interface couplings. Furthermore, the two DWs detach
from each other when the torque increases above a critical value. The critical
field and the highest possible velocity of the DW depending on several factors
are revealed and discussed. Bases on the calculated results, we propose a
method to modulate efficiently the multi DWs in antiferromagnet, which
definitely provides useful information for future AFM spintronics device
design.
