Several magnetic orders in CrBr₃ crystals

The variety of two-dimensional (2D) materials increases day by day, vastly expanding the range of phenomena that can be investigated in two dimensions, as well as the types of van der Waals (vdW) heterostructures that can be created. Recently obtained 2D magnets are more sensitive to external perturbations, which opens vast possibilities and ways of controlling magnetism in them. The magnetic properties of two-dimensional and even bulk van der Waals materials can depend significantly on the structure. For example, CrI₃ crystals have ferromagnetic interlayer coupling, whereas just a few layers of CrI₃ have an antiferromagnetic interlayer interaction. Moreover, bilayers of CrI₃ and CrBr₃ have different magnetic coupling between layers for different stacking orders. In this work, by using cryogenic magnetic force microscopy we study one of the layered vdW magnet, CrBr₃, in the thickness range from 10 nm up to 800 nm, and discover that several types of magnetic orders can coexist within the same crystal, resulting in a peculiar overlay of different domain patterns in the magnetic force microscopy signal. In such a system, one can observe stripe domains in a few top layers, and less ordered non-periodic domains of inner layers simultaneously, which suggests local antiferromagnetic interlayer coupling on the boundaries of two subsystems. Then, we developed a model which assumes that by applying an external magnetic field, layers of one ordering join another subsystem, which is very different from the response of usual ferromagnetic materials with out-of-plane uniaxial anisotropy.