Controlling Magneto-optical Properties in 2D InSe

Nelson, Jovan Julius

doi:https://doi.org/10.21985/n2-gg8z-0942

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Controlling Magneto-optical Properties in 2D InSe

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Light is a powerful tool for manipulating and probing magnetic states in solid state systems. In particular, optically-induced spin orientation, the ability to orient spin with polarized light, has been extensively utilized in low-dimensional III-V and II-VI semiconductors to pioneer spintronic research. Even though traditional semiconductors have found a wide range of applications, recent research on atomically thin van der Waals materials has revealed intriguing low-dimensional landscapes for optical spin manipulation. Transition metal dichalcogenides are the standard van der Waals semiconductors that have optical selection rules that allow for the coupling between light and spin. These spins states are locked to valleys, a pseudospin state that is the basis of valleytronics. Yet, TMDs can be limited by spin-valley locking, a phenomenon that strongly couples carrier spin projection to momentum, making it difficult to freely manipulate pseudospin states. In contrast, it is much easier to freely manipulate spins in traditional semiconductors. Platforms that possess free spin manipulation can be more viable candidates for information applications. Recently, another class of layered materials, III-VI monochalcogenides, has gained significant attention due to their favorable electronic, optical, and magnetic characteristics. Amongst this general class of materials, the optoelectronic attributes of Indium Selenide (InSe) have been seen as considerably beneficial. In addition, there are predictions of spin-polarized optical selection rules near the $\Gamma$ point, implying no spin-valley locking in layered InSe. In this dissertation, optically-induced spin orientation is verified in InSe, opening the door for controlling optical spin phenomena in a van der Waals material with robust electronic and optical properties. Following this result, this body of work presents studies that reveal fundamental physics governing optical spin dynamics in InSe. When all of these properties are considered together, they motivate future research. In particular, combining InSe with 2D magnets for enhanced control over optical spin phenomena. Although there are still many unanswered questions, this dissertation contributes significantly to the body of knowledge of optical spin properties in InSe. Ultimately, aiding the exploration of InSe's potential for future spintronic applications.

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