Discovery and Control of Skyrmions in 2D van der Waals Magnets

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Non-technical AbstractEngineering magnetic materials has led to ground-breaking discoveries in data storage (hard-drives, records), sound engineering (electric guitars, speakers), transportation (bullet trains, suspensions), and many others. This federally funded project aims to take traditional magnetism into nanometric dimensions to realize atomic-scale magnetic patterns resembling a hedgehog’s spikes, called skyrmions. Skyrmion formation offers new functionalities in logic and information storage that are not possible in traditional magnetic materials. Through this funding, the team aims to realize skyrmions in atomically thin materials, understand their magnetic behavior, and manipulate their properties. While doing so, the project aims to discover novel classes of magnetic materials and technologies that will increase the U.S military and economic competitiveness at a global scale and open ways to realize high-performance and next-generation applications towards quantum memory, logic, and communication devices. The immediate societal impacts of the project will manifest through high-school, undergraduate and graduate student training in an active research environment as well as K-12 outreach efforts to introduce students to STEM fields and materials science. Technical AbstractMagnetic skyrmions are topologically protected nanometric size spin textures with exciting quantum properties towards information and neuro-inspired technologies. To date, the experimentally known skyrmionic platforms are restricted to bulk crystals and metallic multilayer films. The ultimate goal of this project is to experimentally stabilize skyrmions in two-dimensional (2D) and van der Waals layered materials and investigate emergent properties arising from reduced dimensions. The project will use transition metal dihalide monolayers and their moiré superlattices as a platform and it will combine theoretical and experimental studies to explore three different mechanisms for skyrmion realization: 1) inversion symmetry breaking in ferromagnetic monolayers, 2) tunable electric fields in ferromagnetic monolayers, 3) twistronics in homobilayers. The project will utilize magneto-optical Kerr, Lorentz microscopy, and diamond-NV atomic force microscope techniques to experimentally understand their magnetic properties. Density functional and Monte-Carlo studies will offer theoretical insights for complete understanding of these 2D skyrmionic platforms. The results from this project will fill a large fundamental knowledge gap in the field by establishing what hallmark characteristics are important for skyrmion formation in the monolayer and few-layer limit. Societal impacts of the project will manifest through new applications towards memory, logic, and communication devices and through cutting edge K-12 and general public outreach activities.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.