Magnetoresistance and magnetic behaviors of the oxide-diluted magnetic semiconductor Zn1-xCoxO thin films

Abstract

We report on the magnetoresistance and magnetic properties of the oxide-dilitted magnetic semiconductor Zn1-xCoxO (x = 0.02 - 0.25) thin films grown on sapphire substrates by pulsed laser deposition. Magnetization measurements show almost paramagnetic behavior with a large negative value of the Curie .Weiss temperature, corresponding to a stronger antiferromagnetic exchange coupling than Mn-doped ZnO. The injection of itinerant electrons over 10(19) cm(3) is achieved by Al doping. Magnetoresistance measurements for n-type Zn1-xCox:Al reveal three qualitatively different behaviors depending on the Co concentration, We observe a giant positive magnetoresistance as large as 60 % for x = 0.20 at 5 K.