Formation process and superparamagnetic properties of (Mn,Ga)As nanocrystals in GaAs fabricated by annealing of (Ga,Mn)As layers with low Mn content
2011 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 84, no 24, 245306- p.Article in journal (Refereed) Published
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-temperature (400 degrees C) and high-temperature (560 degrees C and 630 degrees C) annealing of (Ga,Mn)As layers with Mn concentrations between 0.1% and 2%, grown by molecular beam epitaxy at 270 degrees C. Decomposition of (Ga,Mn)As is already observed at the lowest annealing temperature of 400 degrees 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% and 2% 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.
Place, publisher, year, edition, pages
2011. Vol. 84, no 24, 245306- p.
Condensed Matter Physics Engineering and Technology
Research subject Engineering Science with specialization in Solid State Physics
IdentifiersURN: urn:nbn:se:uu:diva-164877DOI: 10.1103/PhysRevB.84.245306ISI: 000297934500005OAI: oai:DiVA.org:uu-164877DiVA: diva2:470543