Dielectric property of LaAlO₃ thin films doped with magnetic Co and Co₃O₄ clusters

The thin films of Co-doped and Co₃O₄-doped dielectric LaAlO₃ (LAO) by co-ablation of magnetic metal Co and dielectric LAO on Pt - Ti - SiO₂ - Si substrates have been prepared by pulsed laser deposition. A significant enhancement of dielectric constant of LAO upon doping of Co and cobalt oxide clusters is observed. Furthermore, modulation of the dielectric constant of the thin films by applying a magnetic field is verified, obviously due to the ferromagnetism of Co metal and Co oxide clusters embedded in the LAO thin films. A series of microstructural and dielectric characterizations on the as-prepared thin films have been performed and the mechanism underlying the dielectric enhancement upon the doping of Co and Co₃O₄ clusters is discussed.