  The layered metamagnet CrSBr offers a rich interplay between magnetic,
optical and electrical properties that can be extended down to the
two-dimensional (2D) limit. Despite the extensive research regarding the
long-range magnetic order in magnetic van der Waals materials, short-range
correlations have been loosely investigated. By using Small-Angle Neutron
Scattering (SANS) we show the formation of short-range magnetic regions in
CrSBr with correlation lengths that increase upon cooling up to ca. 3 nm at the
antiferromagnetic ordering temperature (TN ~ 140 K). Interestingly, these
ferromagnetic correlations start developing below 200 K, i.e., well above TN.
Below TN, these correlations rapidly decrease and are negligible at
low-temperatures. The experimental results are well-reproduced by an effective
spin Hamiltonian, which pinpoints that the short-range correlations in CrSBr
are intrinsic to the monolayer limit, and discard the appearance of any
frustrated phase in CrSBr at low-temperatures within our experimental window
between 2 and 200 nm. Overall, our results are compatible with a spin freezing
scenario of the magnetic fluctuations in CrSBr and highlight SANS as a powerful
technique for characterizing the rich physical phenomenology beyond the
long-range order paradigm offered by van der Waals magnets.
