Ferromagnetic MnAs Nanocluster Composites Position-Controlled on GaAs (111)B Substrates toward Lateral Magnetoresistive Devices

Selective‐area growth and magnetic reversals of ferromagnetic nanoclusters on semiconducting substrate for magnetic logic applications

“…As observed in the AFM image in Fig. (c), we have successfully formed the MnAs NC composites with a high degree of uniformity by introducing AlGaAs nano‐pillar buffers before the growth of the MnAs NCs . (We concluded that the stripes with a relatively‐dark contrast between the NC composites, which are visible in the AFM image of Fig.…”

“…(b) to be approximately 20 nm. In our previous study, we observed that the interfaces between the crystal facets in the NC hexagons tended to be rounded when two MnAs NCs formed in close proximity with a spatial gap of around 10 nm or less . On the other hand, the NC hexagons mostly had well‐defined crystal facets when there were two MnAs NCs with a spatial gap of around 60 nm or more .…”

“…GaAs (111)B substrates covered with periodic SiO 2 mask opening array patterns for the selective‐area growth of elongated ferromagnetic MnAs NC composite arrays. The details on the substrate preparation and the specifications of the SiO 2 ‐masked substrates for the growth have been given elsewhere . We fabricated the initial mask patterns with elongated mask openings in a triangular lattice arrangement to grow the MnAs NC composite arrays.…”

“…We developed selective‐area metal‐organic vapor phase epitaxy (SA‐MOVPE) to demonstrate the bottom‐up formation of ferromagnetic MnAs NCs on semiconducting (111)B substrates to avoid possible problems caused by the statistical fluctuations. We used SA‐MOVPE because it enables us to control the size, shape, number, position, and spatial arrangement of not only the ferromagnetic MnAs NCs , but also the vertical free‐standing semiconducting NWs, which are promising building blocks for future nanoelectronics and photonics . NWs fabricated using the FM III–V hybrids or diluted magnetic semiconducting materials have recently been created using a conventional vapor‐liquid‐solid (VLS) method and thermal annealing after the deposition or ion beam implantation of the Mn nanoparticles onto the VLS‐grown NWs for nanospintronic device applications using NWs .…”

“…In our previous study, we observed that the interfaces between the crystal facets in the NC hexagons tended to be rounded when two MnAs NCs formed in close proximity with a spatial gap of around 10 nm or less [24]. On the other hand, the NC hexagons mostly had well-defined crystal facets when there were two MnAs NCs with a spatial gap of around 60 nm or more [24]. Although further experiments are required to clarify the detailed mechanisms in the crystal facet formation of the NCs, those with the spatial gap of around 20 nm observed in the current work had a relativelyrounded, i.e., not well-defined, interface between the crystal facets.…”