Effect of Strain on Electronic and Magnetic Structure of Fe-doped CoFe$_{2}$O$_{4}$*

The development of new materials with large room temperature spin polarizations and small conductivity mismatches with semiconductors is key for more complex spintronics devices. CoFe$_{2}$O$_{4}$ has a high Curie temperature (T$_{C}$ = 793 K), a large predicted spin polarization, and, when doped with iron, a conductivity similar to semiconductors; however, the magnetic properties of thin films are different from the bulk. To investigate the effect of strain, Co$_{1-x}$Fe$_{2+x}$O$_{4}$ thin films (0 $\le x\le $ 0.65) are grown epitaxially on MgO (001) and SrTiO$_{3}$ (001) by MBE. UPS probes filled valence band states, while X-ray Linear Dichroism (XLD) determines d-orbital occupations. SQUID magnetometry and XMCD are used to determine bulk and site-specific magnetic moments, respectively. These measurements allow us to understand how strain affects the electronic and magnetic structure of Co$_{1-x}$Fe$_{2+x}$O$_{4}$ thin films.