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