Ferromagnetism and infrared electrodynamics of GaMnAs

ORAL

Abstract

In this work we experimentally address both the magnetic and the electronic properties of the prototype dilute magnetic semiconductor Ga$_{\mathrm{1-x}}$Mn$_{\mathrm{x}}$As using infrared (IR) spectroscopy. We first examine the relationship between the carrier density, determined through a sum-rule analysis of our data and additional IR data available in the literature, and the ferromagnetic transition temperature T$_{\mathrm{C}}$. Our analysis supports the conclusion that the Fermi level resides within a Mn-induced IB, and that the location of the Fermi level within the band plays a key role in controlling T$_{\mathrm{C}}$. Additionally, we perform a detailed examination of the spectral features observed in the IR data of our Ga$_{\mathrm{1-x}}$Mn$_{\mathrm{x}}$As films, and show that these features are also consistent only with a Mn-induced IB scenario. In this latter vein, we will discuss and resolve controversies in the literature related to the peak in a broad mid-IR resonance observed in Ga$_{\mathrm{1-x}}$Mn$_{\mathrm{x}}$As IR spectra.

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Authors

  • B.C. Chapler

    • University of California San Diego

  • S. Mack

    • University of California Santa Barbara

  • R.C. Myers

    • The Ohio State University

  • Kenneth S. Burch

    • Department of Physics and Institute for Optical Sciences, University of Toronto
    • University of Toronto
    • Department of Physics, University of Toronto

  • Nitin Samarth

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

  • D.D. Awschalom

    • Center for Spintronics and Quantum Computation, Univ. of California Santa Barbara
    • Center for Spintronics and Quantum Computation, University of California, Santa Barbara, California 93106, USA
    • Center for Spintronics and Quantum Computation, University of California, Santa Barbara, California 93106
    • Department of Physics and California Nanosystems Institute, University of California, Santa Barbara
    • University of California Santa Barbara
    • Center for Spintronics and Quantum Computation, University of California, Santa Barbara, CA, 93106
    • Center for Spintronics and Quantum Computation, University of California, Santa Barbara

  • Dmitri Basov

    • University of California - San Diego
    • University of California San Diego
    • University of California, San Diego