Magnetic properties of ball-milled FeAl nanograins

Ball milled alloys were investigated by X-ray diffraction, magnetic measurements and Mössbauer spectroscopy. No magnetic saturation is observed up to 5 T and neither the magnetization nor the Mössbauer measurements show a well-defined phase transition but a gradual disappearance of the magnetism with increasing temperature. The hyperfine field distributions and the X-ray grain size data enable the identification of Fe atoms with magnetic moments as some atomic layers' thick surface of the nonmagnetic nanometric Fe–Al grains. The unusual magnetic behaviour is attributed to the large magnetic anisotropy of the low dimensional magnetic surfaces