Magnetometry on systems consisting of nanosized particles

Magnetometry means gaining information about magnetic properties. SQUID-magnetometry, neutron depolarisation and Mossbauer effect spectrometry are examples of very useful experimental methods for investigating magnetic systems consisting of small particles. Small in magnetic sense means that the particles represent single domains. Often their dimensions are in the order of nanometers. This kind of particles can be found in many magnetic systems like super-paramagnets, cluster re-entrant spin glasses or nanostructured soft magnetic alloys. In this paper, examples of experiments performed with these techniques will be discussed. Magnetisation measurements performed on nano Ni-particles fixed in space, neutron depolarisation measurements on re-entrant spin glasses (i.e. disordered Fe-Ni-Mn alloys) and transmission Mossbauer effect measurements on nanostructured soft magnetic materials (Fe-Nb-Cu-Si-B) with the use of high frequency magnetic fields will be considered. The physical understanding of all these processes is strongly supported by the basic assumptions and properties of Stoner-Wohlfarth particles. (C) 2001 Elsevier Science BY All rights reserved.