Magnetic behaviour of nanoclusters SnO2 doped with Fe

CLAUDIA E. RODRÍGUEZ TORRES; A.F. CABRERA; F.H. SÁNCHEZ

La Plata, Argentina

Workshop; Hyperfine Interactions at La Plata-International Workshop; 2005

Ferromagnetism in diluted magnetic oxides is one of the most interesting new problems in magnetism. Many research groups have focused on doping TiO2[1] and ZnO[2] with transition metals. Recently, Co, Fe and Mn doped SnO2 have been explored and interesting results were reported, especially in the case of the Co doped system where a giant magnetic moment was found (7.5 mB/at. per Co at room temperature) [3]. In this work we present a magnetic and structural characterization by x-ray diffraction (XRD), Mössbauer effect spectroscopy (ME), ac-susceptibility and vibrating sample magnetometry (VSM) of SnO2 doped with 10 at.% of Fe prepared by mechanical alloying. XRD indicates a good dissolution of Fe in the SnO2 structure. ME shows that Fe atoms behave paramagnetically (or superparamagnetically), 40 % of them in the Fe+3 state and 60% in the Fe+2 one). The ac-susceptibility measurements present a behaviour consistent with a system of magnetically coupled single domain particles (interacting superparamagnet), or even a cluster glass system. The magnetization results display the typical shape of the superparagnetic regime (in agreement with ME and ac-susceptibility) but a weak hysteresis has been observed.