A publication with Helen Gomonay and Tobias Wagner revealing ultrafast domain wall motion in Mn2Au through permalloy capping has been published in Physical Review B.
Antiferromagnets offer much faster dynamics compared to their ferromagnetic counterparts but their order parameter is extremely difficult to detect and control. So far, controlling the Néel order parameter electrically is limited to only very few materials where Néel spin-orbit torques are allowed by symmetry. In this work, they show that coupling a thin ferromagnet (permalloy) layer on top of an antiferromagnet (Mn2Au) solves a major roadblock—the controlled reading, writing, and manipulation of antiferromagnetic domains. They confirm by atomistic spin dynamics simulations that the domain wall patterns in the Mn2Au are imprinted on the permalloy, therefore allowing for indirect imaging of the Néel order parameter. Their simulations show that the coupled domain wall structures in Mn2Au-Py bilayers can be manipulated by either acting on the Néel order parameter via Néel spin-orbit torques or by acting on the magnetization (the ferromagnetic order parameter) via magnetic fields. In both cases, they predict ultrahigh domain wall speeds on the order of 8.5 km/s. Thus, employing a thin ferromagnetic layer has the potential to easily control the Néel order parameter in antiferromagnets even where Néel spin-orbit torques are forbidden by symmetry. The controlled manipulation of the antiferromagnetic order parameter provides a promising basis for the development of high-density storage and efficient computing technologies working in the THz regime.