Date of Award
Physics and Astronomy
Barry L. Zink
Maria M. Calbi
Anomalous nernst effect, Magnetics, Non-local spin valves, Seebeck coefficient, Spintronics, Thermal engineering
Non-local spin valves (NLSVs) are a valuable tool in the growing field of spintronics due to their unique ability to separate charge current from pure spin current. Their potential applications as read heads for hard-disk drives, as well as use as logic gates and other spin sensors, makes detailed understanding of their behavior under a wide range of operating conditions very important.
In this dissertation, I present results of extreme thermal engineering of the supporting substrate of NLSVs, which has a dramatic impact on the background signal of the device as well as contributions from thermal spin effects such as the anomalous Nernst effect. With use of two-dimensional finite-element modeling of the thermal profile across the NLSV, this yields a value for the anomalous Nernst coefficient (anomalous Nernst angle) for permalloy (Ni80Fe02) of 0.17, in good agreement with other published work. I then extend this successful model to a wider range of temperatures and device geometries to investigate the temperature dependence of the anomalous Nernst angle. Finally, I propose a new membrane-supported measurement circuit to test the effect of the nanowire shape on the absolute Seebeck coefficient of a material at a wide range of temperatures, in order to determine the effect this may have on our calculated values. I also show two-dimensional finite-element models as proof of concept for these new circuits.
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Bennet, Rachel K., "2D Confinement of Thermal Gradients in Metallic Non-local Spin Valves" (2020). Electronic Theses and Dissertations. 1723.
Received from ProQuest
Rachel K. Bennet