A. X. Gray, J. Minar, S. Ueda, P. P. Stone, Y. Yamashita, J. Fujii, J. Braun, L. Plucinski, C. M. Schneider, G. Pannaccione, H. Ebert, O. D. Dubon, K. Kobayashi, and C. S. Fadley
Nature Materials 11, 957-962 (2012)

In a recent publication Jan Minar, Jürgen Braun and Hubert Ebert as part of a multi-institutional collaboration of researchers report on a new technique to probe bulk electronic structure called HARPES (Hard x-ray Angle-Resolved Photo Emission Spectroscopy). They used this technique to investigate the prototypical dilute magnetic semiconductor Ga1-xMnxAs and as reference undoped GaAs. The authors compared the experimental data with their theory based on the coherent potential approximation and fully relativistic one-step-model photoemission calculations including matrix-element effects. Direct observation of Mn-induced states between the GaAs valence band maximum and the Fermi level, centered about 400 meV binding energy, as well as changes throughout the whole range of the valence band, indicates that ferromagnetism in Ga1-xMnxAs must be considered to arise from both p-d and double exchange, leading to a coherent picture for the electronic structure of this interesting and challenging material.