High temperature ferromagnetism in GaAs-based heterostructures with Mn δ doping -: art. no. 017201

We show that suitably designed magnetic semiconductor heterostructures consisting of Mn delta (delta)-doped GaAs and p-type AlGaAs layers, in which the locally high concentration of magnetic moments of Mn atoms are controllably overlapped with the two-dimensional hole gas wave function, realized remarkably high ferromagnetic transition temperatures (T-C). A significant reduction of compensative Mn interstitials by varying the growth sequence of the structures followed by low-temperature annealing led to high T-C up to 250 K. The heterostructure with high T-C exhibited peculiar anomalous Hall effect behavior, whose sign depends on temperature.