Magnetism and magnetic neutron scattering
Contact: Jörg Weissmüller
In conventional ferromagnets, the magnetic moments of each domain are aligned along one of the energetically preferred crystal directions ("easy axes"). However, in nanocrystalline ferromagnets, the direction of the easy axes jumps on the scale of grain size (i.e., a few nanometers). If the ferromagnetic exchange length is greater than this scale, the magnetization cannot follow the jumps. This has significant consequences for the macroscopic magnetic behavior. Magnetic neutron small-angle scattering is often the only way to study the variation in spin (mis-)orientation in volume and with the required resolution of nanometers. In addition, the method of field-dependent magnetic neutron small-angle scattering developed by us allows the quantitative investigation of magnetic interaction terms such as exchange coupling as well as the strength and spatial structure of the anisotropy field.
This work is done in cooperation with PD Dr. Andreas Michels.