[en] In line with this work the strucural and magnetic properties of the exchange coupled layered systems Fe/FeSn₂ and Fe/FeSi/Si and of the Fe ion implanted diluted magnetic semiconductor (DMS) SiC(Fe) were investigated. The main measuring method was the isotope selective ⁵⁷Fe conversion electron Moessbauer spectroscopy (CEMS), mostly in connection with the ⁵⁷Fe tracer layer technique, in a temperature range from 4.2 K to 340 K. Further measurement techniques were X-ray diffraction (XRD), electron diffraction (LEED, RHEED), SQUID magnetometry and FMR (Ferromagnetic Resonance). In the first part of this work the properties of thin AF FeSn₂(001) films and of the exchange-bias system Fe/FeSn₂(001) on InSb(001) were investigated. With the application of ⁵⁷Fe-tracer layers and CEMS both the Fe-spin structure and the temperature dependence of the magnetic hyperfine field (B_hf) of FeSn₂ could be examined. The evaporation of Fe films on the FeSn₂ films produced in the latter ones a high perpendicular spin component at the Fe/FeSn₂ interface. In some distance from the interface the Fe spins rotate back into the sample plane. Furthermore ⁵⁷Fe-CEMS provided a correlation between the absolute value of the exchange field vertical stroke He vertical stroke and the amount of magnetic defects within the FeSn₂. Temperature dependent CEMS-measurements yielded informations about the spin dynamics within the AF. The transition temperatures T_B^*, which were interpreted as superparamagnetic blocking temperatures, obtain higher values compared to the temperatures T_B of the exchange-bias effect, obtained with magnetometry measurements. The second part of this work deals with the indirect exchange coupling within Fe/FeSi/Si/FeSi/Fe multilayers and FeSi diffusion barriers. The goal was to achieve Fe free Si interlayers. The CEMS results show that starting from a thickness of t_FeSi=10-12 A of the ''lower'' FeSi layers the interdiffusion of Fe is inhibited. For thicker FeSi layers (t_FeSi ∼ 20 A) the formation of the metastable defective c-FeSi phase was detected. For the first time an oscillating antiferromagnetic exchange coupling between the Fe layers with a period of ∼ 6 Aas a function of the FeSi thickness. In the third part of this work we attempted to produce a diluted magnetic semiconductor by ion implantation of ⁵⁷Fe into SiC(0001) wafer. For doses ≥ 2 x 10¹⁶ ions cm^-2 and after thermal annealing superparamagnetic Fe₃Si nanoclusters were found with CEMS, XRD and TEM (Transmission Electron Microscopy), which were epitaxially embedded in the SiC matrix. Besides Fe₃Si no other phases were observed. For the lowest doses of 1 x 10¹⁶ ions cm^-2 the CEM spectra at 4.2 K gave evidence of ferromagnetism and the absence of nanoparticles. The upper limit under which there are no segregations of secondary phases was therefore limited to 1-3 at.% Fe. (orig.)