Deciphering Interfacial Dzyaloshinskii-Moriya Interaction in Transition-Metal Dichalcogenide/Permalloy Heterostructures by Brillouin Light Scattering and First-Principles Calculations.

Development of energy-efficient spintronics demands spin-orbit effects and chiral spin textures. The latter requires the Dzyaloshinskii-Moriya interaction (DMI) and its interplay with Heisenberg exchange. Understanding the relative strengths of Heisenberg exchange and interfacial DMI (iDMI) and its scaling with spin-orbit coupling (SOC) is key to stabilizing chiral spin textures in nonmagnet/ferromagnet heterostructures. Here, Brillouin light scattering (BLS) spectroscopy is employed to determine the iDMI and Heisenberg exchange stiffness constants for large-area chemical vapor-deposited monolayer two-dimensional (2D) transition-metal dichalcogenides (TMDs) (MoS, MoSe, WS, and WSe) interfaced with permalloy (Py) thin films. Both symmetric and antisymmetric exchange interactions exhibited a nearly identical dependence on SOC strength for all four interfaces. The origin of the interfacial exchange interaction is underpinned with the help of first-principles-based analysis of TMD/Py interfaces, in which the theoretically calculated intersite exchange parameters and the respective adiabatic magnon spectra reproduce the experimental trend. This study deciphers the origin of iDMI in TMD/ferromagnet heterostructures and their quantification by BLS, highlighting a possible route for the stabilization of chiral spin textures in such systems.