Magnetism in Nanostructures studied with Neutron Scattering

Dr. Artur Glavic
Deepak Singh

Magnetic systems on the range of nanometers are of great interest for application as well as fundamental physics. When macroscopic magnetic materials are scaled down to the nanoscale the energy balance changes and single-domain and super-paramagnetic states arise. When such systems are in close proximity to each other the dipole-dipole interaction becomes important and complex new magnetic correlations can arise. In addition, the contact to other materials at interfaces introduces new interactions that can lead to emergent phaenomena like the giant magneto resistance effect that is present in our everyday life in the read-heads of magnetic HDDs.


While there was and still is a large interest from the scientific community in these systems the magnetic order on these lengths scales is hard to study. Only few techniques exist that have the required spatial resolution and sensitivity to magnetism. While there have been great advances in various microscopy techniques with magnetic sensitivity they have their limitations. The resolution is often in the 25-100nm range, they sometimes rely on resonances of certain elements and they only provide local information from the surface of the sample. For buried structures and to access the global ensemble of a statistically distributed state neutron scattering is still the method of choice, as the magnetic moment of the neutron can directly interact with the sample magnetization.


I will present neutron methods for the study of surface near magnetic nanostructures. Starting from the one dimensional case of polarized neutron reflectometry (PNR) to measure layered magnetic structures over the "bulk" small angle neutron scattering (SANS) technique to the surface sensitive grazing incidence neutron scattering (GISANS), all relevant techniques will be covered. In addition to the relevant techniques, I will discuss some general background relevant to the scattering physics as well as examples of scientific systems.