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Carrier localization in quaternary Ga<sub>1-x</sub>Mn<sub>x</sub>As<sub>1-y</sub>P<sub>y</sub> ferromagnetic semiconductor films

ORAL

Abstract

Motivated by the fact that holes in the Ga1-xMnxAs family of ferromagnetic semiconductors play a key role in determining their ferromagnetic properties, we have measured hole concentrations in a series of three Ga1-xMnxAs1-yPy alloys grown by MBE with varying amounts of phosphorus and fixed Mn. This was carried out by anomalous Hall Effect measurements on a series of samples (10%<y<22%), both annealed and as grown. By comparing the total hole concentrations obtained from the number of acceptors and compensating donors to the Hall carrier density, we find that the number of itinerant holes is significantly less that the total hole concentration. This indicates that a sizable fraction of those holes become localized with increasing P concentration, reaching a high resistivity regime for y=21% at low temperature. We also find that the Curie temperature described by the Zener model is determined by the itinerant holes rather than by the total hole concentrationOur results indicate that that ferromagnetism in Ga1-xMnxAs1-yPy vanishes when the total hole concentration falls below a certain Mott-like threshold, suggesting that the holes reside in the acceptor impurity band created by the Mn acceptors.

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Presenters

  • Logan Riney

    University of Notre Dame, Physics, University of Notre Dame, Department of Physics, University of Notre Dame

Authors

  • Logan Riney

    University of Notre Dame, Physics, University of Notre Dame, Department of Physics, University of Notre Dame

  • Sining Dong

    University of Notre Dame, School of Electronic Science and Engineering, Nanjing University

  • Xinyu Liu

    University of Notre Dame, Physics, University of Notre Dame, Department of Physics, University of Notre Dame

  • Lei Guo

    Shanghai Institute of Ceramics, Chinese Academy of Sciences

  • Ren-Kui Zheng

    Shanghai Institute of Ceramics, Chinese Academy of Sciences

  • Jiashu Wang

    University of Notre Dame, Physics, University of Notre Dame, Department of Physics, University of Notre Dame

  • Xiang Li

    University of Notre Dame, Physics, University of Notre Dame

  • Seul-Ki Bac

    University of Notre Dame, Physics, University of Notre Dame, Department of Physics, University of Notre Dame

  • Jacek Kossut

    Institute of Physics, Polish Academy of Sciences

  • Malgorzata Dobrowolska

    University of Notre Dame, Physics, University of Notre Dame, Department of Physics, University of Notre Dame

  • J K Furdyna

    University of Notre Dame, Physics, University of Notre Dame, Department of Physics, University of Notre Dame

  • Badih A Assaf

    University of Notre Dame, Physics, University of Notre Dame, Department of Physics, University of Notre Dame