Epitaxial Co metal thin film grown by pulsed laser deposition using oxide target

• Epitaxial Co metal film grown by PLD from oxide target exploiting the composition inhomogeneity of the corresponding plasma.
• Magnetic property corresponds to that of Co metal film reported earlier.
• The growth of Co metal film from its oxides provides an opportunity to grow multilayer of metal and oxide system in the PLD.

We report here the growth of epitaxial Co-metal thin film on c-plane sapphire by pulsed laser deposition (PLD) using Co:ZnO target utilizing the composition inhomogeneity of the corresponding plasma. Two distinct plasma composition regions have been observed using heavily alloyed Co0.6Zn0.4O target. The central and intense region of the plasma grows Co:ZnO film; the extreme tail grows only Co metal with no trace of either ZnO or Co-oxide. In between the two extremes, mixed phases (Co+Co-oxides+Co:ZnO) were observed. The Co metal thin film grown in this way shows room temperature ferromagnetism with large in-plane magnetization ~1288 emu cm−3 and a coercivity of ~230 Oe with applied field parallel to the film–substrate interface. Carrier density of the film is ~1022 cm−3. The film is epitaxial single phase Co metal which is confirmed by both X-ray diffraction and transmission electron microscopy characterizations. Planar Hall Effect (PHE) and Magneto Optic Kerr Effect (MOKE) measurements confirm that the film possesses similar attributes of Co metal. The result shows that the epitaxial Co metal thin film can be grown from its oxides in the PLD.