Study of magnetic state of Sn0.9Fe0.1O2 powders at low temperature

We report on magnetic state at low temperatures of oxide diluted magnetic semiconductor powders (Sn0.9Fe0.1O2) prepared by ball milling technique as a function of milling time. After 2 h of mechanical work, the crystallites of SnO2 reach its minimum size (nearly 10 nm) and do not evolve with increasing duration of milling. The magnetic state of the dopant of ground samples by 2, 5 and 10 h is mainly magnetically ordered at low temperatures in contrast to the mainly paramagnetic behavior at room temperature. The change of the state becomes evident from the magnetization curves of zero field cooling-field cooling, reinforced by the Mössbauer measurements at 4.2 K and AC-susceptibility (16-325 K). Combining these results with measurements of magnetization versus applied magnetic field at 5-10 K, it can be concluded that in 5 h milled sample all the Fe incorporated into the rutile structure shows superparamagnetic behavior at RT and they are magnetically ordered at low temperature. Milling times less or greater than 5 h lead to the occurrence of spurious phases.