Structural, electronic, and magnetic properties of single MnAs nanoclusters in GaAs

Journal Article · Mon Dec 08 00:00:00 EST 2014 · Applied Physics Letters

DOI:https://doi.org/10.1063/1.4904097· OSTI ID:22395480

Mauger, S.; Koenraad, P. M. ^[1]; Rench, D. W.; Samarth, N. ^[2]

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1. Department of Applied Physics, Eindhoven University of Technology, Den Dolech 2, 5612 AZ Eindhoven (Netherlands)
2. Department of Physics and Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

MnAs nanoclusters in GaAs were investigated with cross-sectional scanning tunneling microscopy. The topographic images reveal that the small clusters have the same zinc-blende crystal structure as the host material, while the larger clusters grow in a hexagonal crystal phase. The initial Mn concentration during molecular beam epitaxy growth has a strong influence on the size of the clusters that form during the annealing step. The local band structure of a single MnAs cluster is probed with scanning tunneling spectroscopy, revealing a Coulomb blockade effect that correlates with the size of the cluster. With a spin-sensitive tip, for the smaller clusters, superparamagnetic switching between two distinct states is observed at T = 77 K. The larger clusters do not change their magnetic state at this temperature, i.e., they are superferromagnetic, confirming that they are responsible for the ferromagnetic behavior of this material at room-temperature.

• OSTI ID: 22395480
• Journal Information: Applied Physics Letters, Vol. 105, Issue 23; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0003-6951
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ANNEALING
CONCENTRATION RATIO
CRYSTAL GROWTH
CRYSTAL STRUCTURE
CRYSTALS
FERROMAGNETISM
GALLIUM ARSENIDES
MAGNETIC PROPERTIES
MANGANESE ARSENIDES
MOLECULAR BEAM EPITAXY
NANOSTRUCTURES
SCANNING TUNNELING MICROSCOPY
SOLID CLUSTERS
SPIN
SUPERPARAMAGNETISM
TEMPERATURE RANGE 0273-0400 K
TUNNEL EFFECT