Spin and magneto transport in van der Waals heterostructures of graphene with ferromagnets

Sammanfattning: The increasing demand for information and communication technologies has augmented the requirements of electronic devices with improved speed, sensitivity, and reduced power consumption. The utilization of novel electronic materials and the use of the spin degree of freedom as a state variable for information processing and storage are expected to fulfill these demands. In this direction, two-dimensional (2D) materials have attracted a significant research effort with the long-term goal of creating electronic devices with novel functionalities. Graphene has shown excellent potential for future device applications due to its outstanding electronic carrier mobility and spin coherence time at room temperature. Followed by the successful advent of graphene, a vast plethora of 2D materials with complementary electronic properties have been discovered, such as insulating hexagonal boron nitride (hBN), magnets and topological semimetals. We observed that engineering 2D material heterostructures by combining the best of different materials in one ultimate unit offers the possibility of the creation of new phases of matter and novel opportunities in device design. For example, graphene is shown to acquire magnetic properties because of proximity-induced interactions with a magnetic insulator in van der Waals heterostructure. On the other hand, topological semimetal candidates such as WTe2 and ZeTe5 allowed us to observe unconventional charge-to-spin conversion and anomalous Hall effects due to their enormous spin-orbit coupling, lower crystal symmetry, and larger fictitious magnetic field in the crystals. Furthermore, the performance of heterostructures comprised of graphene and hBN with one-dimensional ferromagnetic edge contacts and a path for optimizing such device geometry is outlined. These experimental findings on 2D materials and heterostructure device architectures can contribute to developing a new platform for spintronic as well as quantum science and technology.