Influence of ordered arrangements of cluster chains on the hopping transport in GaAs:Mn/MnAs hybrids at low temperatures

Abstract

Two different arrangements of cluster chains consisting of elongated MnAs nanoclusters were deposited on (111)B-GaAs substrates by selective-area metal-organic vapor-phase epitaxy. This method allows one a controlled positioning of the nanoclusters on the substrate, offering the possibility to investigate the influence of the nanocluster arrangement on the transport properties of granular hybrid structures. Magnetotransport measurements at low temperatures were performed for both cluster-chain arrangements prepared. In contrast to GaAs:Mn/MnAs hybrids with a random cluster distribution, which usually show a negative magnetoresistance at low temperatures, large positive magnetoresistance effects are observed for cluster-chain arrangements at 15 K. Furthermore, the arrangements exhibit a rectifying behavior of the current-voltage characteristics in the presence of an external magnetic field. The magnitude of both effects correlates with the arrangement of the chains on the substrate and can be explained qualitatively by assuming hopping conduction as the dominant transport mechanism.

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

“…The magnetic properties, such as the magnetotransport and MR effects, of the NC arrays were tuned by controlling the size, shape, and arrangement of the ferromagnetic MnAs NCs on the semiconducting substrates using our SA‐MOVPE techniques , and by specially designing the MR device structures . In addition, we proposed magnetic sensor devices that were based on the ordered planar arrangements of the connected MnAs NCs in accordance with the theoretical calculation results .…”

Selective-area growth and magnetic characterization of MnAs/AlGaAs nanoclusters on insulating Al2O3 layers crystallized on Si(111) substrates

“…The SA-MOVPE is promising as it enables us to accurately adjust the size, shape, number, position, and spatial arrangement of the MnAs NCs [16][17][18][19] within the hybrids to tune its magnetic and magnetotransport properties. 3,[20][21][22] Ordered planar arrangements of coupled NCs show large MR effects 23 and MR ratios of 300% are predicted by theory. 24 However, it was observed that Mn provided during the NC growth diffused into the undoped semiconducting layers, in which it was incorporated as an acceptor yielding a p-type conductive diluted magnetic semiconducting layer.…”

Analysis of magnetic random telegraph noise in individual arrangements of a small number of coupled MnAs nanoclusters

“…Growth of high-quality MnAs nanoclusters by selective-area metal-organic vapor-phase epitaxy (SA-MOVPE) offers a number of advantages in the design of lateral magnetoelectronic device structures as degrees of freedom such as size, shape, and position can easily be * matthias.elm@exp1.physik.uni-giessen.de tuned and controlled [21][22][23]. Recently, a spin-valve-like behavior was reported for an arrangement of two MnAs nanoclusters [20,24].…”