The existence of the THz gap in the electromagnetic spectrum is not only preventing the advancement of several technologies but also hindering research and developmental activities due to a lack of research facilities operating in the gap region. There is a plethora of materials with dynamics lying in the THz gap region whose study could potentially lead to the development of new technologies for the generation, detection, and processing of THz signals. Antiferromagnets are gaining recent interest due to their high frequency dynamics lying in the THz region, and their potential uses as active elements in THz spintronics devices have been suggested. This dissertation focuses on the study of insulating antiferromagnets for their potential use in future THz spintronic devices. The first chapter is the introductory one. In the second chapter we focus on the development of a state-of-the-art continuous polarization tunable quasi-optical measurement system operating in the frequency range 220GHz-1.1THz, at temperatures 5K-300K and a maximum magnetic field of up to 9T. The operation of this custom designed system is discussed, and initial results from the test measurements on MnF2 single crystals verify its capabilities. In the third chapter we discuss results from a detailed spectroscopic study performed on two stoichiometric compounds of a novel two-dimensional antiferromagnetic insulator from the MnBi2Te4(Bi2Te3)n family with n=1 and 2. The motion of the antiferromagnetic modes with the direction of applied magnetic field reveal the anisotropic nature of the system, characterized by an easy magnetic symmetry axis and a corrugated hard plane that change slightly with the stoichiometry variation. Our results show how the transition temperature also varies between n=1 and n=2 compounds, indicating that the exchange interaction originating from the antiferromagnetic order changes with the interlayer configuration. In the last chapter we discuss our results on single electron transistor measurements where we realize a stable 1- and 2-input single molecule logic gates.
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Del Barco, Enrique
Doctor of Philosophy (Ph.D.)
College of Sciences
Length of Campus-only Access
Doctoral Dissertation (Open Access)
Khatri, Gyan, "Terahertz Spintronics with Antiferromagnetic Insulators" (2022). Electronic Theses and Dissertations, 2020-. 1590.