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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

Författare:
  • Janusz Sadowski (Dr)
  • Jaroslaw Domagala (Dr)
  • Roland Mathieu (Dr)
  • Andras Kovacs (Dr)
  • Takeshi Kasama (Dr)
  • Rafal Dunin-Borkowski (Prof)
  • Tomasz Dietl (Prof)
Publiceringsår: 2011
Språk: Engelska
Sidor: 245306-1-245306-8
Publikation/Tidskrift/Serie: Physical Review B
Volym: 84
Nummer: 24
Dokumenttyp: Artikel
Förlag: American Physical Society

Sammanfattning

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.

Disputation

Nyckelord

  • Physics and Astronomy
  • molecular beam epitaxy
  • nanomagnetism
  • magnetic semiconductors

Övriga

Published
Yes
  • ISSN: 1098-0121

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