Emission Mossbauer spectroscopy study of fluence dependence of paramagnetic relaxation in Mn/Fe implanted ZnO

Emission Mossbauer Spectroscopy following the implantation of radioactive precursor isotope Mn-57(+) (T-1/2 = 1.5 min) into ZnO single crystals at ISOLDE/CERN shows that a large fraction of Fe-57 atoms produced in the Mn-57 beta decay is created as paramagnetic Fe3+ with relatively long spin-lattice relaxation times. Here we report on ZnO pre-implanted with Fe-56 to fluences of 2x10(13), 5x10(13) and 8x10(13) ions/cm(2) in order to investigate the dependence of the paramagnetic relaxation rate of Fe3+ on fluence. The spectra are dominated by magnetic features displaying paramagnetic relaxation effects. The extracted spin-lattice relaxation rates show a slight increase with increasing ion fluence at corresponding temperatures and the area fraction of Fe3+ at room temperature reaches a maximum contribution of 80(3)% in the studied fluence range.