Formation of magnetic nanoclusters in Fe implanted amorphous and crystalline SiO2.

Conversion electron Mössbauer Spectroscopy (CEMS) studies have been conducted on Fe implanted amorphous and crystalline SiO₂ which were annealed in air up to a temperature of 1000^oC. For both samples, dramatic changes set in after the 1000^oC anneal and the CEM spectra are dominated by strong ferromagnetic sextets. In the amorphous sample, the sextet is characterized by magnetic hyperfine fields of 33T, 31T and 29 T, consistent with the formation α-Fe nanoclusters. In the crystalline sample the ferromagnetic sextet has spectral parameters of δ = 0.38(3) mm/s and B_hf = 52.3T, consistent with formation of α-Fe₂O₃ clusters, reflecting the precipitation of the implanted Fe into such clusters. The line ratios of lines 1, 2 and 3 (and 6, 5 and 4) of the sextet are 3:4:1, reflecting alignment of the magnetic moment of the precipitates normal to the c-axis of the sample surface. [ABSTRACT FROM AUTHOR]