Magnetization and spin distribution of single sub-monolayers of MnTe in semiconductor quantum wells

The magnetization of single, ultrathin MnTe layers embedded in nonmagnetic quantum wells is studied by magneto-optical spectroscopy as well as by numerical simulations. It is shown to be proportional to the Zeeman splitting and thus it can be directly deduced from the magneto-optical experiments. The inverse of the experimentally determined magnetization measured as a function of temperature clearly demonstrates deviations from Curie-Weiss behavior due to the antiferromagnetic coupling between the Mn ions. By fitting this temperature dependence, an approximate Mn diffusion profile is obtained for each sample. The fitting procedure takes into account the antiferromagnetic coupling between the Mn ions as well as the exchange interactions between the Mn ions and the photoexcited electrons. For this purpose we have numerically solved the two-dimensional Ising model by a Monte Carlo method giving the magnetization of two-dimensional layers as a function of magnetic field, temperature, and Mn concentration.