Antiferromagnetic phase transition in a single MnTe monolayer

We investigate a quantum-well sample containing a monolayer of MnTe in its center. The exciton Zeeman splitting is measured as a function of temperature by polarization-dependent photoluminescence excitation experiments. The dependence of the inverse Zeeman splitting shows a kink at a critical temperature of 50 K. Simultaneously, a peak in the linewidth of the View the MathML source–View the MathML source transition is observed at the same temperature. The critical temperature agrees very well with the predicted Nèel temperature obtained within the mean-field approximation for a single monolayer MnTe. After annealing the sample, the Zeeman splitting drastically increases and no critical phenomena are observed anymore.