Relationship among magnetic response and nanoscale structure on innovative materials: the role of XAFS and XMCD probes.

Materials presenting special magnetic and magnetotransport properties such as magnetoresistance, perpendicular magnetic anisotropy (PMA), spin carrier selection (half metals), multiferroic response and so on, are stimulating the research interest owing the possibility of innovative applications and devices. These peculiar magnetic properties generally originate from a fascinating interplay between electronic, structural and magnetic degrees of freedom stimulating the fundamental research. In this field the X-ray absorption spectroscopy provides local structure (XAFS: x-ray absorption fine structure) and local magnetic (XMCD: x-ray magnetic circular dichroism) probes, specially suited to investigate structural, chemical and magnetic properties down to the atomic scale. In-depth XAS studies may provide surprising results, helpfull to understand the special response of these compounds. Representative examples of special compounds are presented in which nanoscale structural and chemical fluctuations definitively (and some time unexpectly) affect their macroscopic response.