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Formation process and superparamagnetic properties of (Mn,Ga)As nanocrystals in GaAs fabricated by annealing of (Ga,Mn)As layers with low Mn content

Sadowski, Janusz LU ; Domagala, Jaroslaw; Mathieu, Roland; Kovacs, Andras; Kasama, Takeshi; Dunin-Borkowski, Rafal and Dietl, Tomasz (2011) In Physical Review B (Condensed Matter and Materials Physics) 84(24). p.1-245306
Abstract
X-ray diffraction, transmission electron microscopy, and magnetization measurements are employed to study the structural and magnetic properties of Mn-rich (Mn,Ga)As nanocrystals embedded in GaAs. These nanocomposites are obtained by moderate (400 C) and high temperature (560 and 630 C) annealing of (Ga,Mn)As layers with Mn concentrations between 0.1 and 2%, grown by molecular beam epitaxy at 270oC. Decomposition of (Ga,Mn)As is already observed at the lowest annealing temperature of 400 C for layers with initial Mn content of 1% and 2%. Both cubic and hexagonal (Mn,Ga)As nanocrystals, with similar diameters of 7 - 10 nm are observed to coexist in layers with an initial Mn content of 0.5% after higher temperature annealing. Measurements of... (More)
X-ray diffraction, transmission electron microscopy, and magnetization measurements are employed to study the structural and magnetic properties of Mn-rich (Mn,Ga)As nanocrystals embedded in GaAs. These nanocomposites are obtained by moderate (400 C) and high temperature (560 and 630 C) annealing of (Ga,Mn)As layers with Mn concentrations between 0.1 and 2%, grown by molecular beam epitaxy at 270oC. Decomposition of (Ga,Mn)As is already observed at the lowest annealing temperature of 400 C for layers with initial Mn content of 1% and 2%. Both cubic and hexagonal (Mn,Ga)As nanocrystals, with similar diameters of 7 - 10 nm are observed to coexist in layers with an initial Mn content of 0.5% after higher temperature annealing. Measurements of magnetization relaxation in the time span 0.1 – 10 000 s provide evidence for superparamagnetic properties of the (Mn,Ga)As nanocrystals, as well as for the absence of spin-glass dynamics. These findings point to weak coupling between nanocrystals even in layers with the highest nanocrystal density. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
molecular beam epitaxy, nanomagnetism, magnetic semiconductors
in
Physical Review B (Condensed Matter and Materials Physics)
volume
84
issue
24
pages
1 - 245306
publisher
American Physical Society
external identifiers
  • wos:000297934500005
  • scopus:84855427401
ISSN
1098-0121
DOI
10.1103/PhysRevB.84.245306
language
English
LU publication?
yes
id
fa7c0347-1841-42f9-b19e-4a5ede8fa2c7 (old id 2269435)
date added to LUP
2011-12-23 08:16:47
date last changed
2017-02-26 04:02:45
@article{fa7c0347-1841-42f9-b19e-4a5ede8fa2c7,
  abstract     = {X-ray diffraction, transmission electron microscopy, and magnetization measurements are employed to study the structural and magnetic properties of Mn-rich (Mn,Ga)As nanocrystals embedded in GaAs. These nanocomposites are obtained by moderate (400 C) and high temperature (560 and 630 C) annealing of (Ga,Mn)As layers with Mn concentrations between 0.1 and 2%, grown by molecular beam epitaxy at 270oC. Decomposition of (Ga,Mn)As is already observed at the lowest annealing temperature of 400 C for layers with initial Mn content of 1% and 2%. Both cubic and hexagonal (Mn,Ga)As nanocrystals, with similar diameters of 7 - 10 nm are observed to coexist in layers with an initial Mn content of 0.5% after higher temperature annealing. Measurements of magnetization relaxation in the time span 0.1 – 10 000 s provide evidence for superparamagnetic properties of the (Mn,Ga)As nanocrystals, as well as for the absence of spin-glass dynamics. These findings point to weak coupling between nanocrystals even in layers with the highest nanocrystal density.},
  author       = {Sadowski, Janusz and Domagala, Jaroslaw and Mathieu, Roland and Kovacs, Andras and Kasama, Takeshi and Dunin-Borkowski, Rafal and Dietl, Tomasz},
  issn         = {1098-0121},
  keyword      = {molecular beam epitaxy,nanomagnetism,magnetic semiconductors},
  language     = {eng},
  number       = {24},
  pages        = {1--245306},
  publisher    = {American Physical Society},
  series       = {Physical Review B (Condensed Matter and Materials Physics)},
  title        = {Formation process and superparamagnetic properties of (Mn,Ga)As nanocrystals in GaAs fabricated by annealing of (Ga,Mn)As layers with low Mn content},
  url          = {http://dx.doi.org/10.1103/PhysRevB.84.245306},
  volume       = {84},
  year         = {2011},
}