  We realize Mn $\delta$-doping into Si and Si/Ge interfaces using Mn atomic
chains on Si(001). Highly sensitive X-ray absorption fine structure techniques
reveal that encapsulation at room temperature prevents the formation of
silicides / germanides whilst maintaining one dimensional anisotropic
structures. This is revealed by studying both the incident X-ray polarization
dependence and post-annealing effects. Density functional theory calculations
suggest that Mn atoms are located at substitutional sites, and show good
agreement with experiment. A comprehensive magnetotransport study reveals
magnetic ordering within the Mn $\delta$-doped layer, which is present at
around 120\,K. We demonstrate that doping methods based on the burial of
surface nanostructures allows for the realization of systems for which
conventional doping methods fail.
