Ferromagnetism of Manganese–Silicide Nanopariticles in Silicon

Abstract

The annealing-temperature (700–900 °C) dependence of the ferromagnetism of manganese-implanted silicon is investigated. In the annealed samples, the manganese-containing nanoparticles, whose mean size was found to get bigger with temperature, are formed and these samples show ferromagnetism. We obtain evidence that the samples annealed at 800–850 °C produce two kinds of ferromagnets and that one of them offers a coercivity as high as 2500 Oe, suggesting the possibility of Si-based nanostructures with stable ferromagnetism. The origin of these ferromagnetisms is also discussed in conjunction with the size distribution of the nanoparticles.

High-temperature ferromagnetism in Si:Mn alloys

“…For instance, the boundary between the precipitate and the matrix may strongly influence the magnetic characteristics of an individual precipitate nanoparticle. 17,20 Below, we show that the spin-fluctuation scenario for high-temperature ferromagnetism in the finite-size precipitate embedded in the Si matrix is to some extent different from that of the bulk precipitate. We assume here that the interior of a precipitate particle consists of the pure MnSi 1.7 silicide without Mn d defects.…”

“…39,40 In contrast to the above scenario, bulk MnSi 1.7 silicide shows weak itinerant magnetism with an ordering temperature of 47 K and with a very low saturation moment of 0.012μ B /Mn, 11 which are much different from those of the MnSi 2−z nanoparticles in the Si 1−x Mn x materials. 10,17 The mechanism for high-temperature FM ordering in the MnSi 2−z precipitate due to spin fluctuations is presented in our work. Note that the saturation moment for the MnSi 2−z precipitate ( 0.2μ B /Mn) is much smaller than that for Mn 5 Ge 3 .…”

“…We presented these alloys as composed of MnSi 2−z precipitate particles enclosed in the Si matrix. 7,10,17,20 We gave a detailed answer to the crucial question why the magnetization and the Curie temperature of the MnSi 2−z precipitate are much larger, roughly by an order of magnitude, than those of the bulk MnSi 1.7 silicide (Ref. 11).…”

High-temperature diamond-like Si-based ferromagnet with self-organized superlattice distribution of Mn impurity

“…Especially interesting DMS are on basis of elementary silicon semiconductor because of their compatibility with the most widespread silicon technology. Numerous attempts of synthesis ferromagnetic DMS on basis of silicon, doped by 3d -impurities, were undertaken [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] . The problem of synthesis such DMS is even more difficult than in case of III-V compounds because of the close to equilibrium solubility of middle 3d -iron group elements impurities in Si is about 10 16 cm -3 on two order more low, these impurities mainly occupy position of interstitials and show donor properties 23,24 .…”

Structural and magnetic properties of Mn+ implanted silicon crystals studied using X-ray absorption spectroscopy techniques

“…Therefore, it is important to understand the origin of magnetic properties in this kind of materials. Some authors (Zhou et al, 2007;Yabuuchi et al, 2008) linked the presence of ferromagnetism with the formation of the Mn 4 Si 7 nanoinclusions while the others (Misiuk et al, 2006;Osinniy et al, 2008) have not seen this kind of dependence.…”