Topics

• Study of magnetism has evolved rapidly because of the new technological applications. Experimental tools are optimised to cope with the many facets involved: bulk measurements, local and microscopic methods as well as scattering methods. Scattering experiments bring the un-paralleled advantage that a wide range of length scales and a broad time domain can be investigated. Two scattering probes have emerged as unparalleled tools: neutrons and x-rays, and the complementary use of the techniques has led to spectacular progress in the understanding of magnetic properties of solids. Each method shows advantages and drawbacks. On the one hand, the high magnetic sensitivity of neutrons, their low energy and their high penetration into materials have made them the probe of choice for magnetism; however, the low neutron flux available is a severe limiting factor. On the other hand, the characteristics of magnetic resonant x-ray scattering together with high brilliance of synchrotron x-ray beams have pushed this method forward. Comparisons of experimental examples will illustrate these points on the following issues: determination of magnetic structures, origin of magnetic moments and observation of magnetic fluctuations. Contrasting the neutron and x-ray methods should lead to optimised future experiments.