Magnetic Silicon Nanoparticles

Prospects for diamond-structured magnetic Si are investigated experimentally, by model calculations, and numerically. Our theoretical analysis, using bond-orbital, Vienna ab-initio simulation package, and SIESTA calculations, suggest that some diamond-Si imperfection may carry a magnetic moment. In particular, for tetrahedral Si₅ clusters, we calculate a magnetic moment of 4 μB per cluster. These moments are more likely to be observed in nanoparticles, as compared with thin films, due to the larger surface-to-volume ratios of the former and to their more versatile atomic surface structure. Experimentally, we have prepared Si nanoparticles by cluster deposition and found a small magnetization, of 2.9 emu/cm³ at 10 K.