Date of Award
8-1-2026
Degree Name
Master of Science
Department
Physics
First Advisor
Mazumdar, Dipanjan
Abstract
e study of spin-based electronic phenomena, or spintronics, has become increasingly important in materials science and condensed matter physics due to its potentialto enable next-generation magnetic technologies, including advanced memory devices and quantum computing. Central to this field is the relationship between a material’s atomic structure and its physical properties, which requires precise control over synthesis conditions to achieve desired magnetic and electronic behavior. In this work, I investigate the structure–property relationships of several magnetic thin-film systems, each designed to address a specific technological challenge. All films were synthesized using magnetron co-sputtering from elemental magnetic and non-magnetic targets, either at room temperature or elevated substrate temperatures, followed by post-deposition annealing when necessary. The primary focus of this thesis is the hexagonal Fe2MnSn alloy, a material first identified and subsequently developed by our research group as a promising candidate for achieving the perpendicular magnetic anisotropy required for next-generation magnetic memory applications. The synthesis of this ternary phase is particularly challenging because it forms within a narrow temperature window and competes with several binary and elemental phases. To understand its formation and stability, I investigated the phase evolution of Fe–Mn–Sn thin films near the 2:1:1 composition ratio as a function of annealing temperature. I show that between 400 and 550◦C, two binary hexagonal phases—the kagome magnet Fe3Sn2 and Fe5Sn3—together with cubic elemental Fe, are stabilized. i These competing phases disappear at approximately 580◦C, where Fe2MnSn becomes the only stable phase. At temperatures above 600◦C, elemental Mn begins to precipitate and becomes increasingly prominent. Correlating the structural evolution with the measured magnetic and electronic properties reveals several key structure–property relationships that provide insight into the formation and stability of this novel magnetic material. In a separate study, I fabricated compositionally graded Co–Pt thin films designed to stabilize magnetic skyrmions, topologically protected nanoscale spin textures with potential applications in future low-power spintronic devices. Through collaborative work with members of our research group, these graded films were found to exhibit enhanced magneto-optical responses, as measured by Kerr rotation, compared with compositionally homogeneous CoPt films. Furthermore, systematic variation of the growth conditions demonstrated that the magnetic and magneto-optical properties remain remarkably robust, indicating resilience to fabrication-induced variations. This behavior is consistent with the expected stability of topologically protected magnetic states and highlights the potential of graded Co–Pt systems for future skyrmion-based technologies. Together, these studies demonstrate how careful control of thin-film synthesis and processing can be used to engineer magnetic materials with tailored properties. By establishing clear links between crystal structure, phase stability, and magnetic behavior, this work contributes to the development of emerging spintronic materials for memory, information processing, and quantum technologies.
Access
This thesis is Open Access and may be downloaded by anyone.