ORCID

0000-0002-8757-2444

Keywords

Antiferromagnetism, Terahertz, Spin-Pumping, Spintronics, Mesoscopic Physics, Thin-Films

Abstract

Antiferromagnetic spintronics is a budding field, promising applications for next generation computing and telecommunication, due to the inherent stability and terahertz frequency magnetic dynamics which antiferromagnets (AFMs) possess. However, due to the infancy and uniqueness of the field, AFM spin dynamics have yet to be studied to their full extent in the terahertz range. To this end, we describe a custom magnetometry system with continuous frequency operation from 60 GHz to 1.5 THz, complete quasi-optical polarization control, peak magnetic field of 9 T, temperature control from 5-300 K, and three-axis sample rotation. We provide initial results from uniaxial AFM MnF2 single crystals and show that the system is uniquely poised to answer open questions in the field of spintronics from fundamental theory to advanced application. Hematite (α-Fe2O3) is an insulating easy-plane antiferromagnet which exhibits a room temperature canted magnetic phase induced by the super-exchange Dzyaloshinskii-Moriya Interaction (DMI) and possesses enhanced spin pumping and spin transport over uniaxial AFMs. We present a thorough study of spin-to-charge current interconversion in bulk and thin films of (0001) α-Fe2O3/Pt heterostructures. A complete picture of the polarization dependence is offered, and the results demonstrate that coherent spin pumping is generated through excitations of both the acoustic and optical modes, provided that the corresponding selection rules are met for the relative orientation between the microwave magnetic field and the magnetic moment. We show the intricate and novel behavior of coherent spin pumping signals generated from the purely antiferromagnetic, high-frequency optical mode for the first time and our results support the current understanding of spin mixing conductance in antiferromagnetic/non-magnetic interfaces, contrary to recent reports. Furthermore, we discuss the implications of layer thickness on spin-to-charge interconversion, providing a deeper understanding of canted antiferromagnets and their potential use in next generation nanoscale spintronics.

Completion Date

2025

Semester

Spring

Committee Chair

Del Barco, Enrique

Degree

Doctor of Philosophy (Ph.D.)

College

College of Sciences

Department

Physics

Identifier

DP0029305

Document Type

Dissertation/Thesis

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