Electronic Theses and Dissertations

Date

2026

Document Type

Dissertation

Degree Name

Doctor of Philosophy

Department

Physics

Committee Chair

Shawn Pollard

Committee Member

Benjamin Keller

Committee Member

Firouzeh Sabri

Committee Member

Jeffrey Marchetta

Abstract

The performance of spintronics devices such as data storage, magnetic memory, read heads, logic technology and magnetic sensors are driven by a complex interplay of a variety of material parameters, which in turn determine a wide range of performance metrics such as radiation hardness, scalability, speed and energies needed for operation. Magnetic anisotropy represents one of these key material properties influencing magnetization dynamics, and ultimately, functionality of a variety of spintronic devices. Therefore, understanding and controlling magnetic anisotropy is essential for the further development of the devices. While magnetic anisotropy can be intrinsic to a specific material, symmetry breaking is another means by which to control and manipulate magnetic anisotropy. This dissertation explores how broken symmetry can be used to modify magnetic anisotropy in a variety of material systems and explores how this broken symmetry influences magnetization reversal processes. First, we investigate how the interface roughness of aerogel (PCSA) substrates influences magnetic anisotropy of permalloy thin films and patterned structures. We find that the in-plane uniaxial anisotropy is strongly dependent on surface roughness, and this anisotropy modifies the lowest-energy magnetic configuration in patterned Py discs from the usual vortex state to a 7-domain configuration. Second, we explore the role of composition gradients in coercivity and switching processes using a combination of atomistic spin simulations and experimental measurements. Intentionally induced gradients in single layer ferrimagnetic thin films are seen to reduce coercivity, indicating a weakening of out-of-plane anisotropy. Finally, we explored the interfacial effect TMDs on ferromagnetic materials. Underlayer CVD grown 〖WS〗_2 induced in-plane magnetic anisotropy on a Py thin film, with changes to the 〖WS〗_2 surface modifying the anisotropy. By tuning exposure time of the 〖WS〗_2 substrate to an Ar-plasma, we found that the introduction of defects, primarily sulfur vacancies, by the Ar-plasma can suppress interfacial anisotropy. In conclusion, this work demonstrates that interface disorder and composition gradients strongly influence magnetic anisotropy by breaking of symmetry. Controlling magnetic anisotropy through interface engineering is essential for future spintronics device applications.

Comments

Data is provided by the student.

Library Comment

Dissertation or thesis originally submitted to ProQuest/Clarivate.”

Notes

Embargoed until 07-14-2026

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Available for download on Tuesday, July 14, 2026

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