The band structure of a prototypical dilute magnetic semiconductor (DMS), Ga1-xMnxAs, is studied across the phase diagram via infrared and optical spectroscopy. We prove that the Fermi energy (EF) resides in a Mn-induced impurity band (IB). Specifically the changes in the frequency dependent optical conductivity [σ1(ω)] with carrier density are only consistent with EF lying in an IB. Furthermore, the large effective mass (m*) of the carriers inferred from our analysis of σ1(ω) supports this conclusion. Our findings demonstrate that the metal to insulator transition in this DMS is qualitatively different from other III-V semiconductors doped with nonmagnetic impurities. We also provide insights into the anomalous transport properties of Ga1-xMnxAs. © 2006 The American Physical Society.
CITATION STYLE
Burch, K. S., Shrekenhamer, D. B., Singley, E. J., Stephens, J., Sheu, B. L., Kawakami, R. K., … Basov, D. N. (2006). Impurity band conduction in a high temperature ferromagnetic semiconductor. Physical Review Letters, 97(8). https://doi.org/10.1103/PhysRevLett.97.087208
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