Epitaxy and characterization of GaMn(N)As for spin electronics

In this contribution we report on the incorporation of nitrogen into GaMnAs, leading to novel semimagnetic quaternary GaMnNAs compounds. The incorporation of nitrogen into GaAs is well known to change the band structure substantially, causing a pronounced band gap bowing. The motivation for this study is to identify the influence of the nitrogen incorporation on the exchange coupling mechanisms in the semimagnetic GaMnNAs. Possible relevant aspects in this respect are a change of hole masses, a change of the position of the valence band edge relative to the Mn acceptor levels, as well as a change of the distance between the magnetic Mn ions, which could eventually lead to an increase of the Curie temperatures relative to GaMnAs.GaMnNAs layers have been fabricated by MBE, with Mn and N concentrations of around 0.5–1.5%. The structures have been analyzed by X-ray diffraction as well as magnetotransport at magnetic fields of up to View the MathML source. The anomalous Hall effect has been analyzed, indicating that this material is ferromagnetic. Compared to GaMnAs, the Curie temperature is slightly increased. Possible reasons for this behavior are discussed.