Preparation of Co nanoparticles embedded in anatase matrix by pulsed laser deposition

Co nanoparticles embedded in anatase matrix were successfully obtained by pulsed laser deposition. LaSrAlO$_{4}$(001) was used as the substrate, on which a thin epitaxial seed layer of (001) oriented anatase TiO$_{2}$ was fabricated. When depositing Ti$_{1-x}$Co$_{x}$O$_{2}$ on the seed layer, phase separation into anatase TiO$_{2}$ and Co metal took place, and Co nanoparticles were dispersed in an anatase matrix. The TiO$_{2}$ seed layer substantially improved the crystallinity of anatase phase, which is speculated to promote the segregation of Co metal from anatase. TEM-EDS measurements revealed that the size of Co particles increased with increasing film growth temperature. Furthermore, we found that coercivity changed as a function of the particle size, as predicted by theoretical calculations.