Ferromagnetism and spin-dependent transport in magnetic semiconductors

We calculate the electronic states of the Mn-doped semiconductors and show that resonant states are formed at the top of the down spin valence band due to the magnetic impurities and that they give rise to a strong and long-ranged ferromagnetic coupling between Mn moments. These resonant states bring about the spin-dependent resistivity to produce magnetoresistive properties of (Ga–Mn)As and their junctions.