Date of Award

2020

Document Type

Dissertation

Degree Name

Ph.D.

Department

Physics and Astronomy

First Advisor

Barry L. Zink

Second Advisor

Xin Fan

Third Advisor

Maria M. Calbi

Keywords

Anomalous nernst effect, Magnetics, Non-local spin valves, Seebeck coefficient, Spintronics, Thermal engineering

Abstract

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.

Publication Statement

Copyright is held by the author. User is responsible for all copyright compliance.

Provenance

Received from ProQuest

Rights holder

Rachel K. Bennet

File size

390 p.

File format

application/pdf

Language

en

Discipline

Physics

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