Strong Faraday rotation in Ce and Bi comodified epitaxial iron garnet films: Valence control through strain engineering

Abstract

The correlation between lattice-misfit strain and the valence change of cerium was investigated in cerium and bismuth comodified iron garnet epitaxial films. We demonstrated that the transition of the valence state from Ce 4 to Ce3 is triggered by reducing the compressive lattice-misfit strain and that the increase in concentration of Ce3 induces a red-shift of the optical bandgap as well as an enhancement of the Faraday rotation. An extraordinary Faraday rotation of 0.91 deg/m at 1.55 m was achieved in these films by maximizing the concentration of Ce3 through strain engineering. © 2011 American Institute of Physics.