Emergence of electric-field-tunable interfacial ferromagnetism in 2D antiferromagnet heterostructures

Abstract

Van der Waals (vdW) magnet heterostructures have emerged as new platforms to explore exotic magnetic orders and quantum phenomena. Here, we study heterostructures of layered antiferromagnets, CrI₃ and CrCl₃, with perpendicular and in-plane magnetic anisotropy, respectively. Using magneto-optical Kerr effect microscopy, we demonstrate out-of-plane magnetic order in the CrCl₃ layer proximal to CrI₃, with ferromagnetic interfacial coupling between the two. Such an interlayer exchange field leads to higher critical temperature than that of either CrI₃ or CrCl₃ alone. We further demonstrate significant electric-field control of the coercivity, attributed to the naturally broken structural inversion symmetry of the heterostructure allowing unprecedented direct coupling between electric field and interfacial magnetism. These findings illustrate the opportunity to explore exotic magnetic phases and engineer spintronic devices in vdW heterostructures.

One particularly useful feature of van der Waals materials is the ability to combine layers of different materials into a single heterostructure, which can have superior properties than any of the constituent materials alone. Here, Cheng et al. combine two interlayer-antiferromagnetic chromium trihalides, CrI₃ and CrCl₃ in close proximity, and demonstrate ferromagnetic coupling between them.