New Route to Fabricate Ferromagnetic Semiconductors without Transition Metal Elements

Abstract
We propose a new route for ferromagnetic diluted magnetic semiconductors by controlling the impurity-band width (W) and the electron-correlation energy (U) in the partially occupied impurity band in the condition of highly correlated electron system (U>W). Based upon first-principles calculations of K2(S,Si) and K2(S,Ge), we demonstrate that transparent, half-metallic and room-temperature ferromagnetic DMS could be designed even without transition metal elements. The results show that it is possible to fabricate the room-temperature ferromagnets in K2(S,Si) and K2(S,Ge) around 8 at%-impurity concentration.