Observation of antiferromagnetic coupling in delta-MnGa/(Mn,Ga,As) /delta-MnGa trilayers

摘要

We present the magnetic properties of deltam-MnGa/(Mn,Ga,As)/deltam-MnGa trilayers. The spacer layer consists of nominally 2 to 19 monolayers (ML) GaAs, but we have indications for an important incorporation of Mn and the possible formaiton of antiferromagnetic Mn_2As. Antiferromagnetic (AFM) coupling is observed for spacer layer thicknesses of 4 to 14 ML GaAs, ferromagnetic (FM) coupling exists outside this region. The largest observed coupling field was -87.0 mT(-870 Oe) at 17 K for a sample with a 12 ML spacer layer, causing a cross-over between both branches of the hysteresis loop and a negative remanence. In oen sample (16 ML) the coupling changes from AFM at low temperature to FM at room temperature.