M.S. (Master of Science)
Department of Physics
Pinwheel artificial spin ice (ASI) systems fabricated using permalloy nanobars offer tunable control of superconducting vortices in an ASI-superconductor hybrid. Vortex pinningis achieved by tuning the ordering of the ASI’s magnetic charge distribution via an external field to create an optimal potential energy landscape to which superconducting vortex motion can be impeded or pinned. Magnetic charge ordering in a pinwheel ASI is visualized using MuMax3 micromagnetic simulations to aid in characterizing the correlation of charge ordering amongst the spin ice system with the application of the external field. Vortex pinning is characterized in a sample of pinwheel spin ice patterned atop a 100nm thin film of MoGe. DC resistance measurements are conducted when both an out–of-plane field is applied to induce superconducting vortices in the MoGe film and an in-plane field is used to tune the ordering of the ASI’s magnetic charges. Effects of both the strength and orientation of the in-plane field on vortex dynamics are explored by measuring (i) the field amplitude dependence of the dissipation at a fixed field orientation and (ii) the angle dependence of dissipation in a fixed amplitude of the magnetic field. They are accounted for in terms of the ordering of the ASI’s magnetic charges revealed by MuMax3 simulations.
Draher, Timothy, "Magnetic Charge Ordering of Pinwheel Artificial Spin Ice in in-Plane External Magnetic Fields and Its Application For Tunable Vortex Pinning" (2022). Graduate Research Theses & Dissertations. 6985.
Northern Illinois University
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