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

Abstract

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) (MoS₂, MoSe₂, WS₂, and WSe₂) 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.