Significance of the interface regarding magnetic properties of manganese nanosilicide in silicon

Magnetic properties of manganese (Mn) nanosilicide embedded in thin silicon-on-insulator (SOI) layers are investigated. Mn nanosilicide formed by Mn⁺ ion implantation into a thin SOI layer followed by a thermal annealing at 600-900 °C shows soft ferromagnetism or superparamagnetism at 5 K. A monotonic decrease of the saturation magnetization is observed with increasing temperature for post implantation annealing and consequently with increasing mean particle size of nanosilicide. In addition, the magnetization is found to be enhanced when the Si surrounding the Mn nanosilicide is selectively removed. These results indicate that the magnetic moment indeed arises from the nanosilicide and is sensitive to the interface conditions.