Stories of Magnetism: Some New Twists

Yong P. Chen- Purdue Physics

Magnetism, important in many everyday technologies, is a well-studied quantum phenomenon (in fact it is one of the best examples of many-body and correlated quantum phenomenon, which can exist even above room temperatures). The past few years has witnessed the rise of a variety of van der Waals (vdW) layered magnetic “2D materials”.  These materials, including ferromagnets, antiferromagnets, and even candidate spin liquids, have challenged our fundamental understanding of magnetism, where the very existence of 2D magnetism has been somewhat surprising. Meanwhile, these magnetic 2D materials, which can be made down to atomic thickness, are relatively easy to transfer, deform and tune their properties, have presented exciting new opportunities for realizing novel physics and functionalities, and potential applications in spintronics and quantum technologies.

In this talk, I will discuss our recent experimental work on such magnetic 2D materials and related heterostructures.  I will highlight some intriguing findings such as: how stretching a 2D magnet can enhance its magnetism; and how stacking two antiferromagnets (each with zero measured magnetization) can produce an exotic ferromagnet whose magnetization can increase when heated — revealing a new type of magnetism known as “Moire magnetism” with rich phases and behaviors tunable by a voltage and by the relative “twisting” angle when the two magnets are stacked together. Finally, I will explore the interplay and interface between magnetism and topology in these materials and heterostructures, which may pave the way for probing exotic quasiparticles, such as Majorana fermions or even non-Abelian anyons still awaiting to be clearly demonstrated experimentally.