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

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.
Authors:
; ;  [1] ; ;  [2]
  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)
Publication Date:
OSTI Identifier:
22395480
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 105; Journal Issue: 23; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
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