Extensions to the theory of spin-spin interactions in semiconductors doped with Cr²⁺ and Mn³⁺ ions will be introduced and shown to be qualitatively important. Terms beyond the ferromagneticsuperexchange will be included (the Bloembergen-Rowland and two-electron contributions), and the significance of the details of the band structure of the host semiconductor (inclusion of d-orbitals in its tight-binding model) will be discussed. Numerical results will be presented for HgTe:Cr (inverted gap), ZnTe:Cr (open gap), and GaN:Mn (also in its native wurtzite structure) for the following experimentally relevant aspects: the values of the spin-spin exchange integrals, the resulting Curie-Weiss temperatures, the predictions for the concentration x dependence of the Curie temperature T_C(x) (from Monte Carlo simulations as well as from the percolation theory), and also the p-d exchange interaction at the valence band maximum.

Link to lecture video