Magnetoelectric phenomena in single-phase and composite systems

In the present review, the main phenomenology and problematic related some of the most interesting magnetoelectric systems (materials having in the same phase magnetic and ferroelectric order and interaction between them, giving rise to the magnetoelectric effect) is presented. Some single-phase systems as manganites, BiFeO3 and relaxor magnetoelectrics mainly interesting from a fundamental point of view, as well as diphasic composites with a high potentiality in applications are discussed. The coupling between ferroelectric and magnetic activity in magnetoelectric multiferroics opens the possibility of controlling magnetic properties through electric fields and vice versa, giving to these materials a large potentiality for applications in spintronics, multiple state memory elements or novel memory devices which might use electric and/or magnetic fields for read/write operations.