Magnetic and structural investigations on as-grown and oxygen annealed PLD SnO 2 : Co thin films

We report the results of a sequence ofmagnetisation andmagneto-optical studies on laser ablated thin films of ZnCoAlO andZnCoO that contain a small amount ofmetallic cobalt. The results are compared to those expectedwhen all themagnetization is due to isolatedmetallic clusters of cobalt andwith an oxide sample that is almost free frommetallic inclusions. Using a variety of direct magneticmeasurements and alsomagnetic circular dichroismwe find that there is ferromagnetism within both the oxide and themetallic inclusions, and furthermore that thesemagnetic components are exchange-coupled when aluminium is included. This enhances both the coercive field and the remanence. Hence the presence of a controlled quantity ofmetallic nanoparticles in ZnAlO can improve themagnetic response of the oxide, thus giving great advantages for applications in spintronics.