Imaging Magnetic Switching in Orthogonally Twisted Stacks of a van der Waals Antiferromagnet.

Abstract

Stacking van der Waals magnets holds promise for creating new hybrid materials with properties that do not exist in bulk materials. Here we investigate orthogonally twisted stacks of the van der Waals antiferromagnet CrSBr, aiming to exploit an extreme misalignment of magnetic anisotropy across the twisted interface. Using nitrogen-vacancy center microscopy, we construct vector maps of the magnetization, and track their evolution under an external field, in a range of orthogonally twisted compensated and uncompensated configurations differing by the number of layers. We show that twisted stacking consistently modifies the local magnetic switching behavior of constituent flakes, and that these modifications are spatially nonuniform. In the case of compensated component flakes (even number of layers), we demonstrate that the combination of dipolar coupling and stacking-induced strain can reduce the switching field by over an order of magnitude in the sample studied. Conversely, in uncompensated component flakes (odd number of layers), we observe indications of a nonzero interlayer exchange interaction between orthogonally twisted flakes during magnetization reversal, which can persistently modify magnetic order. This work highlights the importance of spatial imaging in investigating stacking-induced magnetic effects, particularly in the case of twistronics where spatial variation is expected and can be conflated with structural imperfections.