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. MnSi 1.7 nanoparticles are the common precipitates, which show exotic magnetic properties in comparison with the MnSi 1.7 bulk phase. In this paper we present the static and dynamic magnetic properties of MnSi 1.7 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.

A comprehensive characterization of the structural and magnetic properties of Fe-implanted rutile TiO2(110) is presented. Fe and FeTiO3 (ilmenite) nanocrystals (NCs) are identified by synchrotron-radiation x-ray diffraction. The majority of Fe NCs are crystallographically oriented with respect to the matrix following the relation Fe(001)[010]∥TiO2(110)[11̱0]. Postannealing induced the out-diffusion of Fe and the growth of FeTiO3 at the cost of Fe NCs. Mössbauer spectroscopy and superconducting quantum interference device (SQUID) magnetometry reveal the corresponding evolution of magnetic properties, i.e., magnetization, and superparamagnetic blocking temperature. We unambiguously identify Fe NCs as the origin of the ferromagnetism. These Fe NCs possess a uniaxial in-plane magnetic anisotropy, such that the two Fe[100] axes are inequivalent.

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InAs with an extremely high electron mobility (up to 40,000 cm(2)/V s) seems to be the most suitable candidate for better electronic devices performance. Here we present a synthesis of inverted crystalline InAs nanopyramids (NPs) in silicon using a combined hot ion implantation and millisecond flash lamp annealing techniques. Conventional selective etching was used to form the InAs/Si heterojunction. The current-voltage measurement confirms the heterojunction diode formation with the ideality factor of η = 4.6. Kelvin probe force microscopy measurements indicate a type-II band alignment of n-type InAs NPs on p-type silicon. The main advantage of our method is its integration with large-scale silicon technology, which also allows applying it for Si-based electronic devices.