ECE Seminar - Controllable Synthesis and Property Manipulation of 2D (nonlayered) Magnetic Nanomaterials
Abstract: Two-dimensional (2D) (nonlayered) magnetic materials have attracted extensive attention due to their abundant structures and novel properties, extending the application prospects for spintronics. However, the controllable synthesis of 2D (nonlayered) magnets and heterostructure remains challenging. Recently, our research has been focused on the controllable synthesis and manipulation of properties in 2D (nonlayered) magnetic materials. Firstly, we propose a comprehensive thermodynamics-triggered competitive growth (TTCG) model that offers a quantitative criterion with multiple factorss to predict and guide 2D nonlayered materials growth. Based on this model, we successfully obtained magnetic ultrathin nanosheets of Fe-based ironene, oxides, and chalcogenides via modified chemical vapor deposition (CVD) method. Furthermore, we have developed a substrate step-guided epitaxial technique for producing 2D wedge-shaped magnetic EuS. On the other hand, we proposed the concept of ‘dative epitaxy’, which breaks the limitation of lattice matching and enables the growth of single-unit-cell Cr5Te8 crystals on monolayer WSe2. Additionally, we design a substrate-assisted molten salt method to synthesize various 2D rare-earth oxyhalides and heterostructures. These investigations provide powerful guidance for the controllable synthesis of 2D (nonlayered) magnetic materials and pave the way for developing new diverse spintronic devices.
Further, these 2D nanoflakes exhibits novel magnetic properties. We explored the unique magnetic domain structures of 2D magnetic materials. For example, we revealed that ultrathin Fe nanoflakes exhibited thickness- and geometrical shape-dependent magnetic vortex structure, which can also be manipulated through external fields observed by Lorentz TEM. In addition, we discovered that the magnetism can be directly and efficiently regulated by current injection in ferromagnetic semimetal Co3Sn2S2. The STT (spin transfer torque) efficiency is as high as 2.4-5.6 kOe MA-1 cm2, which is much higher than that of other materials and has the advantages of simple structure, high efficiency and low power consumption, showing great application potential in ultra-low energy consumption devices. Our findings open the door towards a new paradigm of spintronics that combines magnetism, topology, and metallicity for low-energy consumption memory and computing.
Overall, we developed a series of chemical methods for controllable synthesis of 2D (nonlayered) magnetic materials, studied and manipulated their magnetic properties, paving the way for extending their applications into spintronics devices.
Key words: 2D magnetic nanomaterials, controllable synthesis, magnetism manipulation
Prof. Yanglong Hou is Boya Distinguished professor at Peking University, Fellow of Royal Society of Chemistry, the director of Beijing Key Laboratory for Magnetoelectric Materials and Devices. His research interests are focused on the chemical controlled synthesis of multifunctional magnetic nanostructures, and has developed universal methods to prepare monodisperse magnetic nanomaterials and explored their application in biomedical diagnostic and therapy. So far, he has published more than 240 academic papers with more than 27,000 citations and an H-index of 91. He has applied for 21 patents with 16 patents authorized. He received numerous honors and awards, including the 2nd place National Natural Science Prize in 2019, the award for National Innovation and Enterprise, Beijing Mao Yisheng Youth Science and Technology Award, and Young Chemistry Scientist Award of The Chinese Chemical Society-Royal Society of Chemistry. He has been supported by the National Outstanding Young Scientist Foundation, selected as Changjiang Distinguished Professorship and Leadership of Young Scientist, etc. More than 80 invited reports are made in international and bilateral meetings. He is currently the editorial board of several pretigous journals including Advanced Science and National Science Reviews, etc. and serves as a board member of Chinese Chemical Society.
References
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