Ferromagnetism of Twenty-Period InGaMnAs/InGaAs Quantum Wells with Superlattice Structure

We studied the influence of Mn in multilayer system consisting of twenty layers of InMnGaAs/InGaAs quantum wells (QWs) by low-temperature molecular beam epitaxy (MBE). The incorporation of Mn in the InGaAs was confirmed by X-ray diffraction (XRD) and secondary ion mass spectroscopy (SIMS). A ferromagnetic ordering with a Curie temperature over 300 K of twenty layers of InGaMnAs/InGaAs QW structure grown on high resistivity (100) p-type GaAs substrates was found. Even at low growth temperature, we observed the formation of GaMn clusters responsible for the high-temperature magnetic behavior. These measurements strongly support the formation of GaMn clusters and provide strong evidence of the existence of the GaMn clusters that determines Curie temperature.