Abstract
We report an energy gap for hole photoexcitation in ferromagnetic that is tunable by Mn concentration () and by compensation with Te donors. For , electrical transport is dominated by excitation across this gap above the Curie temperature () of 60 K and by thermally activated hopping below . Magnetization measurements reveal a moment of per substitutional Mn while the large anomalous Hall signal demonstrates that the ferromagnetism is carrier mediated. In aggregate these data indicate that ferromagnetic exchange is mediated by holes localized in a Mn-derived band that is detached from the valence band.
- Received 11 January 2005
DOI:https://doi.org/10.1103/PhysRevLett.95.207204
©2005 American Physical Society