Surface Magnetic Structure of ⁵⁷Fe²⁺ Coated\ γ^_56Fe₂O₃ Particles with and without Adsorbed Cobalt

Abstract

The surface magnetic structure of γ -⁵⁶Fe₂O₃ acicular particles with and without adsorbed Co²⁺ ions was investigated by coating with ⁵⁷Fe²⁺ ions and then employing Mössbauer spectroscopy. The samples were characterized by chemical analysis, transmission electron microscopy, X-ray diffraction and magnetic measurements. The Mössbauer spectra at room temperature consisted of a sextet with broad lines with tails towards zero velocity. At 4.2, K in an applied field of 50, kOe the spin structure is non-collinear especially for the samples with the adsorbed cobalt ions.