The two-dimensional magnon gas in atomically thin magnets

Reducing the energy consumption of information technology is one of the major challenges of the 21st century. A potential way to meet this challenge is to realize information processing based on magnons – wave-like excitations of spins in magnetic materials – and thereby avoid the heating caused by electric currents. Efficient and scalable control of magnon transport and information is a key requirement for its integration in information technology, but has thus far remained an outstanding challenge. We will address this challenge by realizing a controllable two-dimensional (2D) gas of magnons in atomically-thin ‘van der Waals’ magnets. Similar to electron transport in 2D conductors such as graphene, we expect the magnon transport in these 2D magnets to be highly tunable by voltages, strain, and proximity to auxiliary 2D materials. Moreover, the intrinsic 2D nature of the magnon gas should lead to strong magnon interactions, enabling fundamentally new phenomena such as topologically-protected and dissipationless magnon transport. To realize a controllable 2D magnon gas, we will focus on van der Waals magnets that are intralayer ferromagnets, but display both interlayer ferromagnetic and antiferromagnetic ordering, such as chromium halides and related compounds. Their magnetic order is tunable by magnetic fields, electric fields, strain, and other 2D materials, providing control over their magnon spectrum and transport properties. We will measure the transport properties of the 2D magnon gas using electrical and optical means, fabricate 2D heterostructures to tune its magnetic parameters, and realize mechanical control of magnons using suspended membranes. Building on these developments, we will create transistor-like devices to reach new regimes of topological, hydrodynamic, and dissipationless spin transport. The demonstration of controllable 2D magnon gases could have an impact comparable to the 2D electron gas that revolutionized classical and quantum electronics, paving the way for new-generation spintronic devices. Our consortium is designed to enable the breakthrough potential of two-dimensional magnon transport. It brings together researchers at different career stages with expertise in van der Waals heterostructure fabrication, magnon-transport theory, and state-of-the-art techniques to detect and control magnons in ultrathin magnets. It builds on successful collaborations and creates a new and crucial connection between the 2D-material and spintronics technologies from Groningen and the membrane and imaging technologies from Delft.