Interlayer Coupling and Magnetoresistance of MnGa/(Mn, Ga, As)/MnGa Trilayers

概要

論文の詳細を見る
We have grown ferromagnetic metal/semiconductor/ferromagnetic metal trilayers with nominal structure [10 nm δMn_<54>Ga_<46>/2-19 monolayers (ML) GaAs/20 nm δMn<_54>Ga<_46>] on GaAs(001) substrates using molecular beam epitaxy. GaAs spacer layers are grown at 300℃ using continuous exposure to a small As flux and pulsed deposition of Ga. They are crystalline but contain a large concentration of Mn, and most likely consist of a mixture or intermediate phase between the diluted magnetic semiconductor Ga_l-_xMn_xAs and the antiferromagnetic metal Mn_2As. We indicate how this Mn contamination can be reduced. All samples show interlayer coupling, which is strong antiferromagnetic (AF) for spacer layer thicknesses of 4-14 ML GaAs, and weaker ferromagnetic (F) outside this range. The temperature dependence of the coupling is different for thin (6-8 ML) and thick (10-16 ML) spacers, suggesting a competition between two different coupling mechanisms. A difference in resistance ΔR=R_P-R_<AP> exists between parallel (R_P) and antiparallel (R_AP) alignment of both MnGa films. The sign of ΔR is correlated with the sign of the interlayer coupling: AF coupling results in ΔR > 0, F coupling results in ΔR < 0. This correlation cannot be explained in the standard model for giant magnetoresistance in magnetic multilayers.
社団法人日本磁気学会の論文
1997-05-01