Enhancement of ferromagnetism in Mn-doped Si via B codoping

Room temperature ferromagnetic Mn0.026BXSi0.974-X bulk samples with X=0.001, 0.005, and 0.01 were fabricated by arc melting and followed by thermal annealing at 1000 degrees C. The effects of carrier density on the ferromagnetism were studied. Due to the high carrier densities, all samples showed metallic behavior. Kondo effect was observed when the temperature was below 10 K. Weakly localized carriers monotonously increased with increasing boron concentration, resulting in the enhancement of exchange coupling among Mn ions. The study indicated that the ferromagnetism originates from the hole mediated Ruderman-Kittel-Kasuya-Yosida mechanism. (C) 2010 American Institute of Physics. [doi:10.1063/1.3352979]