Introduction
In this section, we present a small selection of articles in the areas of magnetism and electronic structure. In particular spin, orbital, charge order, and their interplay have been studied in many different materials. These articles are briefly introduced below.
Magnetic multilayers are very interesting as potential new magnetic recording media. There have been many studies in the last few years and new phenomena are still being discovered. For example, the magnetic coupling in 3d-5d materials is found to be a case of a 'violation' of the pure intra-atomic Hund's rule picture (Wilhelm et al.). Another obvious issue for recording materials, is the speed at which magnetic materials can be switched. Time-resolved studies have shown that dynamic magnetic coupling can be very different from static (Bonfim et al.). A further important parameter for a magnetic material is its magnetocrystalline anisotropy energy. The experimental verification of X-ray magnetic linear dichroism as a direct probe of this quantity is consequently of great significance (Dhesi et al.). Magnetic nanostructures have also been growing in importance, as the quest for denser recording media becomes more pressing. Basic studies of ultrasmall Fe islands show that, here again, unexpected phenomena can be observed (Röhlsberger et al.).
X-ray resonant scattering is an increasingly important probe of charge, magnetic and orbital ordering phenomena. Several examples are given: the existence of 1-dimensional charge order in Yb4As3 is demonstrated (Staub et al.), the first observation of quadrupolar order of the 5f electrons in UPd3 is made (McMorrow et al.), and the interesting coupling between spin and orbital order in KCuF3 is presented (Paolasini et al.). Another interesting study of hydrogenated holmium films can be found in the article by Sutter et al. in Europhys. Lett. 53, 257 (2001).
Charge ordering in magnetite (Fe3O4) has also been studied by very high-resolution powder diffraction (Wright et al.). In addition, novel experiments on the orbital population in the Mott insulator Ca2RuO4 are found in the article by Mizokawa et al. in Phys. Rev. Lett. 87, 077202 (2001).
Although magnetic circular and linear dichroism are relatively mature techniques, work at the ESRF continues to demonstrate that there are many other rich dichroic phenomena to be studied. One recent example is the first observation of X-ray magnetochiral dichroism (Goulon et al.).
Another area where the technique is being rapidly developed is non-resonant inelastic scattering where recent studies of excitons in LiF have extended the potential of this method (Hämäläinen et al., page 76). Also there is current interest in pushing the field of photoelectron spectroscopy into the X-ray range. Experiments on Samarium metal show the potentiality of this field (Dallera et al.).