Structural and size dependent magnetic properties of single phase nanostructured gadolinium-iron-garnet under high magnetic field of 32 tesla

Here we report the single phase nanostructured Gd(3)Fe(5)O(12) garnets with different grain sizes (bulk, 75, 47, 35, and 22 nm) were prepared by ball milling for various milling times. Both the average grain size and the lattice parameter were estimated from the x-ray diffraction line broadening. The (57)Fe Mossbauer spectra were recorded at 300 and 77 K for the samples with different grain sizes clearly evidenced the formation of Fe(2+) ions induced by milling and the content of Fe(2+) increases with milling time. At 4.2 K, a significant increase in saturation magnetization (+11%) has been observed for the 47 nm particles. The magnetization is strongly applied field dependent and no saturation effect is observed even at fields as high as of 320 kOe. The results presented here have been explained in terms of the key role played by the Fe(2+) ions. (C) 2010 American Institute of Physics. [doi:10.1063/1.3357326]