Phase Diagram of Diluted Magnetic Semiconductor Quantum Wells
L. Brey and F. Guinea
Physical Review Letters -- September 11, 2000 -- Volume 85, Issue 11 pp. 2384-2387
Phase diagram of a DMS quantum well, using the parameters described in the text. Full and broken lines represent first- and second-order phase transitions, respectively, between ferromagnetic (F) and paramagnetic (P) phases. In the inset we show the carrier spin polarization for two different densities. The broken line corresponds to  kF = 0.2 nm-1, in this case there is a first-order transition between the x = 1 ferromagnetic phase and the paramagnetic phase. The continuous line corresponds to kF = 0.39 nm-1. Upon lowering the temperature we obtain a continuous transition between the P and the F phases followed by an abrupt transition between two F phases with different values of x . As commented in the text, this last transition is probably spurious.
Phase diagram of a DMS quantum well as a function of   T and magnetic field for a hole density such that  kF = 0.2 nm-1. The line separating the fully polarized from the partially polarized system represents a first-order transition.