Study on 2D Ferromagnet Fe3GeTe2 and its Heterostructures

The van der Waals (vdW) interlayer stacking structure in two-dimensional (2D) magnetic materials gives rise to spontaneous long-range magnetic ordering in few-layer or even single-layer samples at finite temperatures, owing to their strong magnetic anisotropy. Compared with traditional three-dimensional (3D) magnetic thin film materials, 2D ferromagnetic materials can effectively avoid the constraints such as lattice mismatch induced by the substrate and interface defects and terraces produced in the thin-film growth. In addition, the properties of 2D magnetic materials can be more easily modulated by external fields than in the bulk magnetism due to the extremely large specific surface area given by 2D properties. Therefore, 2D magnetic materials bring new opportunities to realize novel spintronic devices with smaller size, higher capacity, faster response, and lower power consumption. Thus, since the experimental confirmation of the first 2D intrinsic ferromagnet in 2017, studies on 2D magnetic materials have quickly become a hot topic attracting international attention. The exploration of this new 2D material family will provide more possibilities for the development of high-performance magnetic sensors and non-volatile magnetic random-access memory in the future. Multifunctional heterojunction devices assembled by stacking 2D magnetic materials are expected to show broad application in aerospace, biomedicine, and other fields. The research on 2D magnetic materials is still in the initial stage, more efforts should be paid to deal with the low Curie temperature (Tc) and the instability under atmospheric conditions by various methods such as applying the electric field, doping and interface engineering. Among many 2D ferromagnets reported previously, Fe3GeTe2 (FGT) exhibits a high Tc, good air stability, and increased TC above room temperature by ionic gate showing great application potential. In addition, a plenty of exciting phenomena, including large anomalous Hall current, topological Skyrmions, exchange bias and antisymmetric magnetoresistance, have been observed in either intrinsic few layer FGT or 2D heterostructures of FGT, demonstrating it is a very alluring candidate for studying both fundamental 2D magnetism and devices