MnSi1.7 nanoparticles embedded in Si: Superparamagnetism with collective behavior

The doping of Mn in Si is attracting research attentions due to the possibility to fabricate Si-based diluted magnetic semiconductors. However, the low solubility of Mn in Si favors the precipitation of Mn ions even at nonequilibrium growth conditions. MnSi1.7 nanoparticles are the common precipitates, which show exotic magnetic properties in comparison with the MnSi1.7 bulk phase. In this paper we present the static and dynamic magnetic properties of MnSi1.7 nanoparticles. Using the Preisach model, we derive the magnetic parameters, such as the magnetization of individual particles, the distribution of coercive fields and the interparticle interaction field. Time-dependent magnetization measurements reveal aging and memory effects, qualitatively similar to those seen in spin glasses.