Illustration: Alan Stonebraker

Figure 1: $(Ga,Mn)As$ is a magnetic semiconductor made from $GaAs$ doped with manganese magnetic impurities. A thin layer of iron (red) grown on top of $(Ga,Mn)As$ can induce an ordering of the manganese magnetic moments (small black arrows). The magnetic order extends over a layer across the interface (middle, yellow) and the induced magnetization is opposite to that of the iron (M). The magnetization of the interfacial layer persists even at room temperature, when the bulk of the $(Ga,Mn)As$ is paramagnetic.