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Magnetocrystalline anisotropy and uniaxiality of MnAs/GaAs(100) films

Författare:
  • J. Magnus Wikberg
  • Ronny Knut
  • Sumanta Bhandary
  • Igor di Marco
  • Mikael Ottosson
  • Janusz Sadowski (Dr)
  • Biplab Sanyal
  • Pal Palmgren
  • Cheuk W. Tai
  • Olle Eriksson
  • Olof Karis
  • Peter Svedlindh
Publiceringsår: 2011
Språk: Engelska
Publikation/Tidskrift/Serie: Physical Review B
Volym: 83
Nummer: 2
Dokumenttyp: Artikel
Förlag: Amer Physical Soc

Sammanfattning

We present an investigation of the magnetic behavior of epitaxial MnAs films grown on GaAs(100). We address the dependence of the magnetic moment, ferromagnetic transition temperature (T-c), and magnetocrystalline anisotropy constants on epitaxial conditions. From thorough structural and magnetic investigations, our findings indicate a more complex relationship between strain and magnetic properties in MnAs films than a simple stretch/compression of the unit cell axes. While a small increase is seen in the anisotropy constants, the enhancement of the magnetic moment at saturation is significant. Results of x-ray magnetic circular dichroism show a behavior of the spin and orbital moment that is consistent with a structural transition at T-c. In particular, we find that the ratio of the orbital to the spin moment shows a marked increase in the coexistence region of the ferromagnetic alpha- and paramagnetic beta-phases a result that is well in accord with the observed increase in the c/a ratio in the same temperature region. The ab initio density functional calculations reveal that the magnetic properties are more sensitive towards change in the ab-plane compared to change in the c-axis which is explained by the analysis of band structures. The effects of electron correlation in MnAs using ab initio dynamical mean field theory are also presented.

Disputation

Nyckelord

  • Physics and Astronomy

Övriga

Published
Yes
  • ISSN: 1098-0121

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