XAS and XMCD spectroscopies to study matter at high pressure: Probing the correlation between structure and magnetism in the 3d metals

The study of the properties of matter under extreme conditions allows reproducing the physical conditions of inaccessible regions of the earth and planets, encountering a geophysical interest. Also it addresses fundamental questions concerning the stability of the crystallographic structure, the magnetic order and the electronic structure thus giving an insight into their own appearance. In this review we illustrate how X-ray absorption spectroscopies, coupled to diamond anvil cell techniques, can be successfully employed at this purpose. As an example, we describe recent advances in the investigation of the ferromagnetic transition metals under high pressure.