Magnetic domain texture and the Dzyaloshinskii-Moriya interaction in systems with perpendicular exchange bias
Hans T. Nembach, Justin M. Shaw
Antiferromagnetic materials present us with rich and exciting physics, which we can exploit to open up new avenues in spintronic device applications. We explore perpendicularly magnetized exchange biased systems of Pt/Co/IrMn and Pt/Co/FeMn, where the crossover from paramagnetic to antiferromagnetic behavior in the IrMn and FeMn layers is accessed by varying the thicknesses. We demonstrate, through magneto-optical imaging, that the magnetic domain morphology of the ferromagnetic Co layer is inuenced by the N_eel order of the antiferromagnet (AFM) layers. We relate these variations to the anisotropy energy of the AFM layer and the ferromagnet (FM)-AFM inter-layer exchange coupling. We also quantify the interfacial Dzyaloshinskii-Moriya interaction (DMI) in these systems by Brillouin Light Scattering spectroscopy. We _nd that the DMI remains unchanged, within experimental uncertainty, for di_erent phases of the AFM layers which allows us to conclude that the DMI is largely insensitive to both AFM spin order and exchange bias. Understanding such fundamental mechanisms is crucial for the development of future devices employing chiral spin textures, such as, N_eel domain walls and skyrmions, in FM-AFM heterostructures.