Photoemission measurements of strained VO2

The metal-insulator transition of VO$_2$ has been a textbook example for many years, despite a clear understanding of its microscopic origins proving elusive. Recently, the promise towards novel applications of high-quality thin films, in which the properties of the transition can be tailored by applied strain, has thrust VO$_2$ back into focus. Here, we report photoemission measurements of strained VO$_2$ thin films epitaxially grown on TiO$_2$(110) and TiO$_2$(100) substrates. The applied strain for these two films lead to moderate and large compressive rutile $c$-axis strains, respectively. By making use of the incident photon polarization, we observe the changes in polarization anisotropy both across the transition and as a function of applied strain, and demonstrate how we can use this to learn more about the origin of the MIT in VO$_2$.