Interlayer Exchange Coupling in Short Period GaMnAs/GaAs Superlattices

T h e low di me nsion al str uctures containin g I II { V ferromagnetic semiconductors w ere intensi vely investigated in the last few years because of the v ariety of their potential applicati ons. T he aim of the present wor k w as to study the interlayer exchange coupling in the short perio d Ga Mn A s/GaA s sup erlattice s containing 16 or 8 GaMnA s monolayers. Samples w ith the magnetic layers corresp ondi ng to the mixed crystal comp osition with 5% or 6% of Mn w ere grow n by M BE techni que and characteri zed by both high-resolu tio n X -ray diraction and Raman scattering metho ds. F olded acoustic phonons w ere observed for the rst time for this particul ar quantum system in the Raman scattering spectra. T he interlayer exchange coupling in selected sup erlattices was investigated by both elastic neutron scattering (diractio n) and p olarized neutron re ectivi ty measurements. Presence of the smo oth interf aces and the stability of the sup erlatti ce perio d w ere conrmed by neutron reectometry data. Ferromagnetic correlation of the magnetizatio n vector in subsequent GaMnA s magnetic layers w as demonstrated by both exp erimental metho ds.