The dzyaloshinskii-moriya interaction in magnetic multilayers

The Dzyaloshinskii-Moriya interaction (DMI) is of large interest from a scientific as well as from a technological point of view. The DMI is an anti-symmetric exchange interaction, which favors perpendicular alignment of neighboring spins [1], [2]. The DMI only exists in systems with broken inversion symmetry. It is for example responsible for the canted spin-structure in α-Fe2O3 (Hematite). It can also exist in magnetic multilayers, where a ferromagnet is in contact with a heavy metal, for example Pt. Interfacial DMI can be described by a three site exchange mechanism, where the coupling between two spins in the ferromagnet is mediated by an atom with large spin-orbit coupling in the adjacent material [3], [4]. It can give to chiral spinchains, chiral domain walls and skyrmions. Nanoscale skyrmions have the potential to be utilized as bits for a novel racetrack memory [5]. Skyrmions promise high stability and they can be generated and propagated by spin-orbit torques.