Spintronics in flatland: controlling magnetism in heterostructures based on 2-dimensional van der Waals magnets
Efficient control of the magnetization orientation in magnetic materials is a central goal in spintronics for enabling next generation magnetic memory technologies. For reliable switching of magnetic order, spin-orbit torques from electrically generated spin currents in heavy metals and topological insulators are the leading candidates. Over the last few years, several experimental breakthroughs have discovered magnetism in 2-dimensional layered van der Waals (vdW) magnets, which are a few atoms thick and can be easily stacked and combined with other materials into devices with atomically sharp interfaces. This opens an exciting new material platform to explore mechanisms that can improve the efficiency of manipulating magnetization by spin-orbit torques as well as to fundamentally probe magnetic proximity effects. While the magnetic ordering and properties of layered vdW magnets have been studied in detail, experimental demonstrations of integrating these materials into useful devices, has been limited.
In this talk, I will highlight our recent experimental results on integrating and probing the layered, insulating vdW magnet Cr2Ge2Te6 (CGT) into heterostructure devices both with heavy metals and with 3-dimensional topological insulators. First, I will show that the magnetization orientation of CGT can be detected electrically and can be manipulated efficiently by current-induced spin-orbit torques from heavy-metals like Pt and Ta at record low switching current densities. Then, I will present results on the first experimental demonstration of strong and controllable interactions between CGT and the topological surface states of a 3-dimensional topological insulator (BiSbTeSe2). I will also discuss the experimental challenges involved and the instrumentation developed to carry out these studies.
Our results successfully establish heterostructures engineered from layered vdW magnets as an excellent platform for improving spintronics devices and for controlling topological magneto-electric effects which are of great interest in developing next-generation electronic devices.