Infrared probe of Ga$_{1-x}$Mn$_{x}$As films with controlled disorder and compensation

ORAL

Abstract

Arsenic antisite defects (As$_{Ga})$ formed due to low temperature growth conditions are a leading cause of disorder and compensation in Ga$_{1-x}$Mn$_{x}$As. Samples grown with gradient As:Ga growth condition for 0.005$<$x$<$ 0.16 have allowed for optimized As flux minimizing As$_{Ga}$. By studying samples at this optimized location via infrared spectroscopy, a new level of precision can be attained in exploring the electronic structure and other intrinsic properties of Ga$_{1-x}$Mn$_{x}$As samples. Using optical sum rule analysis of our experimentally determined optical conductivity ($\sigma _{1}(\omega ))$, we extract the free carrier band mass (m*) and find it to be several m$_{e}$. We also comment on the levels of interstitial Mn (Mn$_{i})$, finding for x $>$ 0.03 roughly 25{\%} of Mn resides at an interstitial location. Additionally, by probing positions along the As:Ga gradient we directly measure the effects of disorder and compensation on these samples. Systematic changes in $\sigma _{1}(\omega )$ as As$_{Ga}$ content is increased are reported, and the consequences of this on our understanding of the electronic structure of Ga$_{1-x}$Mn$_{x}$As are discussed.

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Authors

  • Brian Chapler

    • University of California San Diego

  • Roberto Myers

    • Ohio State University
    • Dept. of Physics, University of California, Santa Barbara CA 93106

  • Shawn Mack

    • University of California Santa Barbara
    • UCSB

  • D.D. Awschalom

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

  • M.C. Martin

    • Lawrence Berkeley National Laboratory

  • A. Dattelbaum

    • Los Alamos National Laboratory

  • Kenneth Burch

    • University of Toronto

  • Dmitri Basov

    • UCSD
    • University of California San Diego
    • Univ. of CA, San Diego
    • University of California, San Diego