Interlayer coupled domain wall dynamics induced by external magnetic field in synthetic antiferromagnets

The response of a magnetic domain wall to an external magnetic field in a perpendicularly magnetized synthetic antiferromagnet is studied using both micromagnetic simulations and a reduced model. It is found that the external field induces a sizable displacement between the position of the domain wall in each layer, which can be larger than the domain wall width for a sufficiently strong field. We also study the dynamic evolution of the system when this field is applied or removed. In both cases we find a complex response with two distinct phases that involve both internal domain wall rotation and coupled interlayer domain wall oscillations. As a result of this dynamics spin waves are radiated. The emitted radiation is characterized by a broadband spectrum and can be detected far away from the domain wall.