In almost all spintronic devices, e.g., those based in spin valves or magnetic tunnel junction structures, ferromagnetic (FM) - antiferromagnetic (AFM) exchange coupled bilayers [1] constitute an essential part for establishing a magnetic reference orientation [2,3]. Moreover, it is well known that a range of novel properties arise, in both FM and AFM materials, as the size is reduced (e.g., increased importance of surface effects, changes in the magnetization reversal modes or superparamagnetism) [4]. However, despite the industrial demand to systematically reduce the size of magnetic devices and the potential size effects in this kind of systems, rather few systematic studies of the effects of size reduction on the FM-AFM coupling exist [5]. Actually, several accounts on the detriment of the exchange bias properties in nanostructures (e.g. reduction of the loop shift [6] or decrease of the blocking temperature [7]) with respect to continuous films have been reported. Some of these effects could actually be a limiting factor for the applicability of certain devices and should thus be taken into account in their design. However, encouraging new phenomena also arise in exchange biased nanostructures, such as the improvement of the thermal stability of nanostructures when exchange coupled to AFMs [8,9] or the existence novel magnetic states not present in unbiased counterparts [10]. In this talk, an overview of different aspects of exchange bias in nanostructures and their relevance for spintronic devices will be presented.
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