Non-local spin-spin coupling in topological semimetals

We study the spin-spin coupling in finite-geometry topological semimetals employing the RKKY theory of interaction among impurity spins. The impurity spins can be on the surface of the geometry, where the mediated interaction between them can be through the topological surface states. Alternatively, the impurity spins can be on opposite surface of the system, where the mediated interaction can be through the semi-metalic bulk states, giving rise to signatures of possible non-local effects.