Spatial extent of the Dzyaloshinskii-Moriya interaction at metallic interfaces

We experimentally investigate the range of the Dzyaloshinskii-Moriya interaction (DMI) occurring at magnetic interfaces within metallic heterostructures. To this aim we perform Brillouin light scattering spectroscopy on a set of Co-based, asymmetric metallic heterostructures, incorporating atomically thin continuous films obtained by room-temperature sputtering, and of identical orientation and quality. We thus get access to the intrinsic dependence of the interfacial DMI and other magnetic interactions on the thickness of the nonmagnetic layer adjacent to Co, which is chosen among Pt, Ru, and Au. Notably, we observe that a robust DMI is already generated by as few as two atomic planes of Pt and that interfacial DMI can be efficiently suppressed by a dusting of Ru equivalent to a single atomic plane coverage. These results point directly towards a mechanism where DMI is generated within the two first atomic planes away from the interface, in agreement with first-principles calculations. This locally generated DMI is, however, likely to be modulated by more distant atoms in the case of strain effects. The short-range aspect of the interfacial DMI opens up the synthesis of dense magnetic multilayers, allowing for a strong interfacial DMI even with very thin layers, which can be further tuned by strain engineering.