On magnetism and the insulator-to-metal transition in $p$-doped GaAs

ORAL

Abstract

Although Ga$_{1-x}$Mn$_{x}$As is often described as the prototypical ferromagnetic semiconductor, many aspects of the electronic structure and nature of mediating carriers remain open. A central question in this regard is whether the insulator-to-metal transition (IMT) in $p$-doped GaAs is significantly modified when dopants are magnetic. We address this through an infrared spectroscopic study of GaAs doped with either non-magnetic Be or magnetic Mn acceptors. Through our comparison, we are able to isolate effects of magnetic dopants in GaAs from those associated with disorder and proximity to the IMT. Here we show Mn-doped samples exhibit an unusual electronic transport regime, combining elements of both metallic and insulating behavior, at doping concentrations far beyond the onset of the IMT. Be-doped films however, reveal genuine metallicity just above the IMT boundary. These results underscore the pivotal role of magnetism in transport and optical phenomena of Ga$_{1-x}$Mn$_{x}$As.

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Authors

  • Brian Chapler

    • University of California San Diego

  • Roberto Myers

    • Ohio State University
    • Department of Physics and Department of Materials Science and Engineering, The Ohio State University, Columbus, OH
    • Department of Materials Science and Engineering, The Ohio State University, Columbus, Ohio

  • S. Mack

    • University of California Santa Barbara

  • A. Frenzel

    • University of California San Diego

  • B.C. Pursley

    • University of California San Diego

  • Kenneth Burch

    • University of Toronto

  • E.J. Singley

    • California State University East Bay

  • A.M. Dattelbaum

    • CINT, Los Alamos National Laboratory
    • Los Alamos National Laboratory

  • N. Samarth

    • Department of Physics and Materials Research Institute, The Pennsylvania State University, University Park, PA 16802
    • Physics Dept., Penn State University, University Park PA 16802
    • Pennsylvania State University
    • Department of Physics and Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
    • Center for Nanoscale Science and Materials Research Institute, Penn State University, University Park PA 16802.

  • D.D. Awschalom

    • Center for Spintronics and Quantum Computation, University of California, Santa Barbara, CA 93106
    • University of California, Santa Barbara
    • University of California Santa Barbara
    • Center for Spintronics and Quantum Computation, University of California, Santa Barbara, CA
    • Center for Spintronics and Quantum Computation, University of California, Santa Barbara
    • Physics Dept., University of California, Santa Barbara CA 93106

  • Dimitri Basov

    • University of California San Diego
    • UCSD
    • Department of Physics, University of California, San Diego