  CrCl3 is a layered insulator that undergoes a crystallographic phase
transition below room temperature and orders antiferromagnetically at low
temperature. Weak van der Waals bonding between the layers and ferromagnetic
in-plane magnetic order make it a promising material for obtaining atomically
thin magnets and creating van der Waals heterostructures. In this work we have
grown crystals of CrCl3, revisited the structural and thermodynamic properties
of the bulk material, and explored mechanical exfoliation of the crystals. We
find two distinct anomalies in the heat capacity at 14 and 17 K confirming that
the magnetic order develops in two stages on cooling, with ferromagnetic
correlations forming before long range antiferromagnetic order develops between
them. This scenario is supported by magnetization data. A magnetic phase
diagram is constructed from the heat capacity and magnetization results. We
also find an anomaly in the magnetic susceptibility at the crystallographic
phase transition, indicating some coupling between the magnetism and the
lattice. First principles calculations accounting for van der Waals
interactions also indicate spin-lattice coupling, and find multiple nearly
degenerate crystallographic and magnetic structures consistent with the
experimental observations. Finally, we demonstrate that monolayer and few-layer
CrCl3 specimens can be produced from the bulk crystals by exfoliation,
providing a path for the study of heterostructures and magnetism in ultrathin
crystals down to the monolayer limit.
