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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
  • Jaroslaw Domagala
  • Roland Mathieu
  • Andras Kovacs
  • Takeshi Kasama
  • Rafal Dunin-Borkowski
  • Tomasz Dietl

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.

Publiceringsår

2011

Språk

Engelska

Sidor

1-245306

Publikation/Tidskrift/Serie

Physical Review B (Condensed Matter and Materials Physics)

Volym

84

Issue

24

Dokumenttyp

Artikel i tidskrift

Förlag

American Physical Society

Ämne

  • Natural Sciences
  • Physical Sciences

Nyckelord

  • molecular beam epitaxy
  • nanomagnetism
  • magnetic semiconductors

Status

Published

ISBN/ISSN/Övrigt

  • ISSN: 1098-0121