  The magnetic properties in two-dimensional van der Waals materials depend
sensitively on structure. CrI3, as an example, has been recently demonstrated
to exhibit distinct magnetic properties depending on the layer thickness and
stacking order. Bulk CrI3 is ferromagnetic (FM) with a Curie temperature of 61
K and a rhombohedral layer stacking, while few-layer CrI3 has a layered
antiferromagnetic (AFM) phase with a lower ordering temperature of 45 K and a
monoclinic stacking. In this work, we use cryogenic magnetic force microscopy
to investigate CrI3 flakes in the intermediate thickness range (25 - 200 nm)
and find that the two types of magnetic orders hence the stacking orders can
coexist in the same flake, with a layer of ~13 nm at each surface being in the
layered AFM phase similar to few-layer CrI3 and the rest in the bulk FM phase.
The switching of the bulk moment proceeds through a remnant state with nearly
compensated magnetic moment along the c-axis, indicating formation of c-axis
domains allowed by a weak interlayer coupling strength in the rhombohedral
phase. Our results provide a comprehensive picture on the magnetism in CrI3 and
point to the possibility of engineering magnetic heterostructures within the
same material.
