Electronic and magnetic properties of iron doped zirconia: Theory and experiment

We systematically investigated, both theoretically and experimentally, Zr_(1-x) Fe_x O_(2-y) ranging from diluted (x ~ 0.05) up to large (x ~ 0.25) Fe concentration. By atomic layer deposition, we grew thin films of high-j zirconia in cubic phase with Fe uniformly distributed in the film, as proven by time of flight secondary ion mass spectrometry and transmission electron microscopy measurements. Iron is in Fe 3þ oxidation state suggesting the formation of oxygen vacancies with y concentration close to x/2. By ab-initio simulations, we studied the phase diagram relating the stability of monoclinic vs. tetragonal phase as a function of Fe doping and film thickness: the critical thickness at which the pure zirconia is stabilized in the tetragonal phase is estimated ranging from 2 to 6 nm according to film morphology. Preliminary results by X-ray magnetic circular dichroism and alternating gradient force magnetometry are discussed in comparison to ab initio data enlightening the role of oxygen vacancies in the magnetic properties of the system