Dzyaloshinskii-Moriya interaction in Pt/Co/Ir and Pt/Co/Ru multilayers films

Magnetic Skyrmions have attracted intense interest since they were discovered in 2009 in B20 magnets. In B20 magnets, in addition to symmetric Heisenberg exchange interaction, there is also a non-trivial anti-symmetric Dzyaloshinskii-Moriya interaction (DMI) which is key to realizing magnetic Skyrmions. In asymmetric magnetic multilayers, large interfacial DMI (iDMI) can be introduced to stabilize Skyrmions. The iDMI has displayed increasingly important roles in the modification of domain walls, stabilization of Skyrmions, and realization of new topological spin textures such as magnetic radial vortices.
However, unlike magnetization and magnetic anisotropy which can be readily measured, iDMI is difficult to measure. By exploring the spin-orbit torque induced effective field under an in-plane bias magnetic field, iDMI can be quantitatively determined in magnetic multilayers [1]. In this work, we study the iDMI in Pt/Co/Ir and Pt/Co/Ru multilayer films using the aforementioned method. We will discuss how the iDMI can be tuned experimentally. Skyrmions have been realized in Pt/Co/Ir multilayers [2]. We find that Pt/Co/Ru multilayer films can also host Skyrmions.

[1] C.-F. Pai, et al., PRB 93, 144409 (2016).
[2] C. Moreau Luchaire, et al., Nat Nano 11, 444 (2016).