This subproject will study the atomic structure of the hybrid material, the electronic band structure, orbital type and other relevant aspects of the edge states using Angle-Resolved Photo-Electron Spectroscopy (ARPES) and advanced scanning probe methods. Spin-polarized scanning tunneling spectroscopy (STS) provides the (spin-filtered) local density of states allowing to study the spin properties and orbital nature of the helical edge states. Kelvin-probe spectroscopy will reveal the local charge density, local electric fields, and position of the Fermi-level. The stability of the helical states with respect to (magnetic) scatterers will be investigated by placing scatterers on certain positions using atomic manipulation, and in-plane and out-of-plane vector magnetic fields.