Description
- Abstract:
- The control of spin currents through interfacial and spin-orbit-driven effects is central to the development of next-generation spintronic technologies. This dissertation investigates how spin-orbit coupling (SOC) and interfacial symmetry govern the generation, transmission, and conversion of spin currents across three model material systems including half-metallic CrO2, RuO2/CrO2 bilayers, and Ru-Pt alloys. These systems were strategically chosen to trace the full pathway of spin manipulation: CrO2 for intrinsic spin polarization and quantum transport, RuO2/CrO2 for interfacial exchange and spin coupling, and Ru-Pt for extrinsic spin-charge conversion. Epitaxial CrO2 thin films serve as a platform for intrinsic spin current generation and quantum transport. Their nearly 100% spin polarization enables robust, coherent spin currents while low-temperature transport measurements reveal quantum oscillations and high mobility, indicative of phase-coherent electronic motion. These results establish CrO2 as an ideal half-metal for generating spin-polarized currents and exploring SOC-influenced quantum transport phenomena. RuO2/CrO2 heterostructures exemplify interfacial exchange and spin coupling where an active spin-orbit antiferromagnetic RuO2 layer interacts with the CrO2 ferromagnet. Magnetization measurements reveal spin reorientation and exchange bias effects, illustrating how SOC and broken inversion symmetry at the interface can modulate spin alignment, interlayer magnetic interactions, and the transmission of spin angular momentum across oxide heterostructures. Ru-Pt alloys provide a model for extrinsic spin-to-charge conversion, where spin currents generated in a ferromagnet are converted into measurable charge signals via the spin Hall effect. Systematic mapping of the spin Hall angle across the full composition range demonstrates how crystal structure and SOC control the efficiency of spin-charge interconversion. Beyond conventional impurity tuning, Ru-Pt demonstrates structural phase evolution as an effective tuning parameter and poses as a promising alternative for spin-orbit torque devices. These results highlight how extrinsic SOC effects can be engineered to detect, manipulate, or generate spin currents in metallic systems. Together, these studies establish a unified framework connecting intrinsic spin generation and interfacial spin coupling to extrinsic spin-to-charge conversion and detection. The results provide insight into design principles for low-power, scalable spintronic devices that exploit SOC and symmetry engineering to control spin currents across diverse material platforms.
- Notes:
- Thesis (Ph. D.)--Brown University, 2026
Citation
Bheemarasetty, Vineetha Sai,
"Mechanisms of Spin and Charge Transport Across Oxide and Alloy Interfaces"
(2026).
Physics Theses and Dissertations.
Brown Digital Repository. Brown University Library.
https://repository.library.brown.edu/studio/item/bdr:pdwba7ad/
