Formation process and superparamagnetic properties of (Mn,Ga)As nanocrystals in GaAs fabricated by annealing of (Ga,Mn)As layers with low Mn content
Author
Summary, in English
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.
Department/s
Publishing year
2011
Language
English
Pages
1-245306
Publication/Series
Physical Review B (Condensed Matter and Materials Physics)
Volume
84
Issue
24
Document type
Journal article
Publisher
American Physical Society
Topic
- Natural Sciences
- Physical Sciences
Keywords
- molecular beam epitaxy
- nanomagnetism
- magnetic semiconductors
Status
Published
ISBN/ISSN/Other
- ISSN: 1098-0121