Local distortions and long range magnetic order in VI3 and CrI3

In 2D van der Waals trihalides ferromagnets MX3 - where M is a transition metal and X a halogen - the local electronic configuration around the metal centres determines both the long range magnetic order and the electronic properties. In CrI3, the typical coordination of Cr atoms is octahedral and most of its known magnetic and electronic properties arise from it. For VI3 instead, it was recently suggested that the electronic character of V d-states stabilizes a trigonal distorted configuration via a Jahn-Teller (JT) mechanism. Nonetheless, local distortions can be induced also in CrI3 by the proximity of an interface such that of a substrate, for instance by the strain acting on an epitaxial single layer. With this experiment, we want to perform X-ray dichroism measurements to understand the orbital and magnetic order in bulk VI3 and a single layer film of CrI3 epitaxially grown in situ on Au(111) and showing strain and coordination distortions.