Towards magnetic control of ultrathin CrSBr layers via substrate interaction

Two-dimensional magnetic materials have recently sparked a lot of interest, but some important challenges need to be overcome in order to unlock their application potential. One of those is the efficient manipulation of their magnetic states, where interactions at the interface level are particularly effective due to their inherent “all surface” character. In this proposal, we aim to investigate effective routes to control the magnetic state of ultrathin CrSBr by using proximity-induced magnetic coupling to a ferromagnetic substrate. CrSBr, an A-type antiferromagnet in the bulk form, possess a particular magnetic structure which is sensitive to easily undergo field-induced spin reorientation transitions and its magnetic manipulation appears thus feasible. Based on promising preliminary results, we aim to study the coupling of CrSBr ultrathin flakes deposited onto ferromagnetic LaSrMnO3 substrates. We employ X-ray magnetic circular dichroism to allow for an element-specific quantification of the magnetic moments located at Cr and Mn sites, respectively, giving a direct and clear correlation of the magnetic coupling on the substrate and the flake domain. By studying CrSBr flakes of different thicknesses spanning from the mono- to the few-layer regime, the range and nature of such interactions can be assessed. One scenario is that only a certain number of CrSBr layers follows the substrate magnetization, whereas the outer layers remain unaffected due to their intrinsic antiferromagnetic interlayer exchange. A second scenario could be a “domino effect”, which results from an initial strong short-range interaction of substrate and CrSBr at the interface that propagates towards the outer layers, changing the direction of the alternating spins. The second scenario will result in an antiferromagnet which can switch its Neel vector dictated by the substrate magnetization. The impact of the expected outcomes is to provide an efficient way to modify magnetic properties of van der Waals antiferromagnets by designer heterostructures.