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.

–

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