Novel Magnetic Instabilities in Semiconductor Double Quantum Wells

We present calculations of the electronic structure and total energy of double quantum wells for an arbitrary spin polarization of the system. This allows us to predict the order (first or second) of the magnetic phase transitions and the temperature range in which experiments should be done. We have found that, up to the present experimental situation, there is no contradiction with a local-density-approximation treatment. We have confirmed the existence of an antiferromagnetic phase and a ferromagnetic phase, but at lower densities than those claimed previously. Moreover, we have found a novel high-density ferrimagnetic phase under accessible electric fields.