Temperature evolution of the magnetic properties of Ag/Fe nanodot arrays

Magnetic nanodot structures have significant potential in spintronic applications. The magnetism of nanodots are predominately influenced by external conditions such as temperature. While the magnetization reversal modes of sub-100 nm Fe nanodots has been reported, currently there is a lack of information about the temperature evolution of the magnetic properties of larger Fe nanodots. In this work, the magnetism of Fe/Ag thin films and nanodot arrays were comparatively analyzed over the temperature range of 2-300 K. A natively-oxidized alpha-Fe2O3 layer was formed at the Fe/SiO2 interface, and this oxide resulted in an exchange bias at low temperatures. The inplane and out-of-plane magnetization reversal modes of nanodot arrays were revealed through the magnetic hysteresis loops' temperature dependence. The contribution of exchange coupling between Fe and alpha-Fe2O3 was also identified through the temperature dependence of the coercivity, exchange bias, and DC susceptibility. Our results provide new insights towards understanding the magnetization dynamics in nanosized magnetic elements.