UCLA

Two-dimensional materials provide a new platform for discovery of exotic physics and phenomena. They possess rich electronic properties, susceptibility to electric control, danglingbond-free interfaces, and readily controlled thicknesses. These properties make them accessible, engineerable, and integrable into emergent heterostructures for previously unachievable properties and applications like atomically-thin magnetoelectric devices for ultracompact spintronics. Although layered materials like graphene are not inherently spin-polarized, magnetic proximity effect-induced spin splitting has been identified as an effective way to realize spin transport in graphene. Except the magnetic proximity effect, recently discovered long-range intrinsic magnetic orders in the van der Waals materials rise fundamental research interests. This dissertation includes the experimental realization of monolayer graphene magnetized by an underlying antiferromagnet. By coupling graphene to an antiferromagnetic thin film, exchange splitting energy as large as 134 meV at 2 K. This exchange splitting energy can be modulated through field coolings, which is reflected through the shifted quantum Hall plateau and quantum oscillations in graphene. Further, magneto-optic Kerr measurement supports magnetism in the graphene at low temperatures. This work establishes a key functionality for future graphene-based spin logic and memory devices. Different from the induced magnetism into graphene, the interface-induced Dzyaloshinskii-Moriya interaction and N�eel-type skyrmion lattice in an intrinsic van derWaals ferromagnetic material Fe3GeTe2 have also been discussed. By coupling Fe3GeTe2 to 1T’-WTe2, a large interfacial Dzyaloshinskii-Moriya interaction can be induced at the interface probably due to the inversion symmetry breaking. Transport measurements have shown the topological Hall effect in this heterostructure for temperatures below 100 K. Furthermore, Lorentz transmission electron microscopy is used to directly image N�eel-type skyrmions along with aligned and stripe-like domain structures. This interfacial coupling induced Dzyaloshinskii-Moriya interaction is estimated to have a large energy of 1.0 mJ/m2, which is much larger than the critical value required to stabilize the N�eel-type skyrmions. This work paves a path towards the skyrmionic devices based on van der Waals layered heterostructure. Based on either induced or intrinsic magnetism in van der Waals materials, possible quantum anomalous Hall insulators and van der Waals heterostructureare listed and proposed.