Spin gain transistor in ferromagnetic semiconductors-the semiconductor Bloch-equations approach

A scheme and principle of operation of a "spin gain transistor" are proposed. A large unmagnetized current creates the carrier density sufficient for the ferromagnetic transition; a small magnetized current initiates spontaneous magnetization. Large magnetized current is then extracted. Thus, spin gain of >1000 is predicted. Collective dynamics of spins under Coulomb exchange interaction is described via semiconductor Bloch equations.