IFLP   13074
INSTITUTO DE FISICA LA PLATA
Although the magnetism of fine particles has been widely studied during the last years, there are a rich variety of phenomena, which remain to be understood in the nanoscale granular systems. A complete understanding of the magnetic properties of these nanoscopic systems is hindered by their inherent complexity, involving broad size distributions, different structural and/or magnetic phases and interparticle magnetic interactions.  In order to get deeper insight into the nanoestructurated metallic systems, allowed powders of (Fe$_{79}$Mn$_{21}$)$_{1-x}$Cu$_{x}$ (x = 0.1 to 0.35) were prepared by milling the elemental species in a horizontal vibrating device with steel ball and vial, under Ar atmosphere during 15h at 33Hz. The structural analysis has been obtained by X-ray diffraction (XRD) and X-Ray Absorption Fine Structure (EXAFS-XANES) at the Fe K-edge and at the Cu K-edge at RT. Mössbauer spectroscopy (MS) and magnetic measurements (AC-susceptibility, ZFC-FC and M vs H) were performed to magnetic characterized the samples. Preliminary XAFS results show changes in the amplitude of the Fourier transformation. The amplitude increases when decreases the Cu content in the sample. XRD and MS results suggest the presence of two FCC-phases with different ordering temperatures. The AC-susceptibility measurements indicate the existence of a characteristic temperature {\it T$_{c}$} ($\sim$ 150 K) which shifts to lower temperatures with increase the Cu content. These results, associated with magnetization measurements as function of temperature and applied field, provide evidence for a highly disordered magnetic system with spin-glass-like behavior.