Memory effect of Mn5_5Ge3_3 nanomagnets embedded inside a Mn-diluted Ge matrix

Crystalline Mn5Ge3 nanomagnets are formed inside a Mn-diluted Ge matrix using Mn ion implantation. A temperature-dependent memory effect and slow magnetic relaxation are observed below the superparamagnetic blocking temperature of Mn5Ge3. Our findings corroborate that the observed spin-glass-like features are caused by the size distribution of Mn5Ge3 nanomagnets, rather than by the inter-particle interaction through the Mn-diluted Ge matrix.Comment: 10 pages, 4 figures,. submitted to Appl. Phys. Let

Nanoscale precipitation patterns in carbon–nickel nanocomposite thin films: Period and tilt control via ion energy and deposition angle

Periodic precipitation patterns in C:Ni nanocomposites grown by energetic ion codeposition areinvestigated. Films were grown at room temperature by ionized physical vapor deposition using apulsed filtered cathodic vacuum arc. We reveal the role of the film composition, ion energy andincidence angle on the film morphology using transmission electron microscopy and grazingincidence small angle x-ray scattering. Under these growth conditions, phase separation occurs in athin surface layer which has a high atomic mobility due to energetic ion impacts. This layer is anadvancing reaction front, which switches to an oscillatory mode, producing periodic precipitationpatterns. Our results show that the ion induced atomic mobility is not random, as it would be in thecase of thermal diffusion but conserves to a large extent the initial direction of the incoming ions.This results in a tilted pattern under oblique ion incidence. A dependence of the nanopatternperiodicity and tilt on the growth parameters is established and pattern morphology control via ionvelocity is demonstrated