Spin Response and Spin Waves in a Two Dimensional Transition Metal Dichalchogenide*

Transition metal dichalcogenide (TMD) monolayers are 2D materials with a direct bandgap. Due to the lack of inversion symmetry and strong spin-orbit coupling (SOC), they are promising candidates for applications, such as vallytronic and spintronic devices. In such systems repulsive interactions among the electrons are found to have an important impact on their band structures, as well as on their topological properties. Because of the important qualitative effects of SOC, spin response is a particularly useful probe of these systems. We report on a theoretical study of spin response functions of this system using the time-dependent Hartree-Fock approximation. Our study shows how collective modes (i.e, spin-waves) can emerge in a simple model TMD with short-range repulsive interactions. We also show that their behavior as a function of chemical potential contains simple signatures of the unique valence band structure in this type of system.