Ferromagnetic (Ga, Mn)As and its heterostructures

Magnetotransport measurements have been performed to clarify the origin of ferromagnetism in a new III-V-based diluted magnetic semiconductor, (Ga, Mn)As. Hall resistance was dominated by the anomalous Hall effect proportional to the magnetization, allowing one to determine the magnetic properties such as Curie temperature and Curie constant as well as the conduction type (p-type) and carrier concentration. Negative resistance above Curie temperature was shown to be well accounted for by the spin disorder scattering, from which the exchange between conduction holes and localized Mn moments was determined. This exchange interaction is shown to be responsible for the observed ferromagnetism in (Ga, Mn)As through the RKKY interaction. The magnetic coupling between two ferromagnetic (Ga, Mn)As films separated by a nonmagnetic (Al, Ga)As layer was controlled by the composition of the intermediary layer, indicating the critical role of the holes in the intermediary layer on the coupling. (C) 1998 Elsevier Science B.V. All rights reserved.