Spin glass like behaviour in nanogranular FeMnCu samples

M. MIZRAHI, A.F. CABRERA, S. J. STEWART, J. DESIMONI

Rio de Janeiro Brasil

Conferencia; LACAME06; 2006

Spin glass like behaviour in nanogranular FeMnCu samples M. Mizrahi, A.F. Cabrera, S. J. Stewart, J.  Desimoni Departamento de Física, Facultad de Ciencias Exactas-UNLP, IFLP-CONICET C. C.N° 67, 1900 La Plata, Argentina. e-mail: desimoni@fisica.unlp.edu.ar Nanogranular magnetic materials have been received much attention in the last decade due to their rich phenomenology and intensively researched from the fundamental and technological point of view. Frustration of the exchange interactions, disorder and surface effects have been claimed to interpret their structural and magnetic properties. In order to get deeper insight into the nanoestructurated metallic systems, allowed powders of (Fe79Mn21)1-xCux (x = 0.2, 0.25 and 0.3) were prepared by milling the elemental species in a horizontal vibrating device with steel ball and vial, under Ar atmosphere during 15 h at 33Hz.  A detailed analysis of structural aspects and magnetic properties has been obtained via Mössbauer spectroscopy (MS), X-ray diffraction (XRD) and magnetic measurements (AC-susceptibility, ZFC-FC and M vs H). The XRD and MS results suggest the presence of two FCC-phases with different ordering temperatures. The AC-susceptibility measurements show the existence of a characteristic temperature Tc (» 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, provides evidence for a highly disordered magnetic system with spin-glass-like behavior.