Comprehensive surface and crystallographic structure investigation of MnGaGe nanoislands grown on GaAs

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The growth of islands with nanometer height and diameter sizes of the ternary compound MnGaGe with tetragonal structure on the GaAs (001) substrate surface was investigated. Topographic analyses performed by atomic and magnetic force microscopy are consistent with the formation of ferromagnetic MnGaGe nanoislands, constituted by the preferential stacking of (001) and (110) planes whose are the most favorable to the epitaxial relationship on the (001) surface of GaAs wafer, not tested yet. As the spontaneous magnetization tends to align preferentially perpendicular to the Mn basal planes of the tetragonal crystallographic structure, one part of the nanoislands has magnetic dipole or even single- domains whose magnetization is in-plane and another part out-of-plane directions, in the remanent state. Kelvin probe force microscopy and ultraviolet photoelectron spectroscopy analysis obtained the work function, not measured in the literature, and indicates the intermetallic character of the MnGaGe nanoislands, whose near-stoichiometry and good crystalline structure are confirmed by energy dispersive X-ray spectroscopy, X-ray diffraction together with nanodiffraction probe and X-ray fluorescence mapping carried out at a synchrotron installation. The high chemical stability of the MnGaGe nanoislands exhibiting ferromagnetism at room temperature with magnetization perpendicular to the substrate is very promising for spintronic applications at nanoscale.