Date of Award
Doctor of Philosophy (PhD)
Physics and Astronomy
My thesis is dedicated to the study of the magnetic interactions and magnetization reversal dynamics in ferromagnetic heterostructures with perpendicular magnetic anisotropy (PMA). Two related projects will be included: 1) investigating interfacial Dzyaloshinskii-Moriya interaction (DMI) in multilayer structures; 2) controlled stripe domain growth in PMA heterostructures. Magneto Optic Kerr Effect microscopy and magnetometry techniques along with vibrating sample magnetometry were used to investigate these phenomena.
The CoPt bi-layer system is a well-known PMA material system exhibiting DMI. However, films with many CoPt bi-layers are known as having zero effective DMI due to its inversion symmetry. I focused my research on CoNiPt tri-layer heterostructures with broken inversion symmetry. In my project, the interfacial DMI as a function of the number of CoNiPt tri-layers in multilayered films was investigated and non-zero DMI in this constructed “bulk” magnetic materials were observed. For the project of stripe domain manipulation, the CoNi bi-layer system with PMA was studied. CoNi “bulk” multilayered materials with PMA allow for controlled direction of stripe domain growth. The formation of variable angle domain intersection segments is comprised of the stripe domains.
Nanayakkara, Jagodage Kasuni S., "DMI Interaction and Domain Evolution in Magnetic Heterostructures with Perpendicular Magnetic Anisotropy." Dissertation, Georgia State University, 2018.