X-ray and Neutron Scattering Studies of Magnetic Domain Dynamics and Spin Structures.

摘要

The study of magnetic spin structures at nanometer length scales and their dynamics is of both fundamental and technological importance. X-rays and neutrons are penetrating probes that are suitable for studying these in the bulk and the interfaces of the materials. In this thesis, the magnetic domain dynamics are studied by resonant soft x-ray scattering together with x-ray photon correlation spectroscopy. The domain fluctuations reveal when the temperature is close to the phase transition temperature. We find the domain wall dynamics in an antiferromagnet corresponds to a collective motion of spins and exhibit some universal features associated with the jamming behavior in many jammed soft condensed matter systems. We also discuss about the utilization of polarized neutron reflectometry to study the interfacial spin structure in an exchange biased bilayer. The magnetization profiles are obtained which show that some spins are not completely reversible when the magnetic field is reversed. These spins include pinned uncompensated spins in the antiferromagnet and the interfacial spins exchange coupled to those spins. A previously established model was found to reproduce the magnetization profile observed. Finally, we carried out a grazing incidence small angle neutron scattering experiment on an optical grating as a way to test the Distorted Wave Born Approximation (DWBA). DWBA is briefly reviewed and we used it to calculate the scattering intensity of the system.