Original Article

Journal of Superconductivity

, Volume 18, Issue 3, pp 315-320

Magnetic Interactions in Granular Paramagnetic–Ferromagnetic GaAs: Mn/MnAs Hybrids

  • W. HeimbrodtAffiliated withDepartment of Physics and Material Sciences Center, Philipps-University of Marburg
  • , P. J. KlarAffiliated withDepartment of Physics and Material Sciences Center, Philipps-University of Marburg
  • , S. YeAffiliated withDepartment of Physics and Material Sciences Center, Philipps-University of Marburg
  • , M. LampalzerAffiliated withDepartment of Physics and Material Sciences Center, Philipps-University of Marburg
  • , C. MichelAffiliated withDepartment of Physics and Material Sciences Center, Philipps-University of Marburg
  • , S. D. BaranovskiiAffiliated withDepartment of Physics and Material Sciences Center, Philipps-University of Marburg
  • , P. ThomasAffiliated withDepartment of Physics and Material Sciences Center, Philipps-University of Marburg
  • , W. StolzAffiliated withDepartment of Physics and Material Sciences Center, Philipps-University of Marburg

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Abstract

The magneto-transport properties of granular paramagnetic–ferromagnetic GaAs:Mn/MnAs hybrids have been studied. Positive and negative magnetoresistivity can be observed in the paramagnetic matrix as well as in the GaAs:Mn/MnAs hybrid system. The experimental results and the respective relevant interactions are discussed. A phenomenological explanation from a microscopic point of view is presented. It is suggested that the paramagnetism of the matrix plays a major role in the magneto-resistive behavior of the hybrids, in contrast to diamagnetic–ferromagnetic hybrids where the magnetoresistance (MR) is dominated by the ferromagnetism of the clusters.

KEY WORDS:

paramagnetic–ferromagnetic hybrids GaMnAs/MnAs magneto-transport