Analysis of magnetic mechanisms of 3d-doped ZnO diluted magnetic semiconductors by an abnormal peak on M-T curve

Abstract

The crystallographic structures and magnetic properties of a Zn 0.95Co0.05O thin film deposited on a C-sapphire substrate using a dual-beam pulsed laser deposition method were characterized. It was shown from crystallographic analysis that the film belongs to the wurtzite structure with the C-axis aligned with that of the substrate. Magnetic hysteresis loops were observed till up to room temperature. A small peak around 55 K was noticed on the magnetization vs. temperature curve. The corresponding temperature of the small peak is close to that of 'the abnormal peak' reported by X.M. Zhang et al. From the results obtained, no correlation was found between the abnormal peak and the quantum effects. The magnetic behaviors in the Zn0.95Co0.05O film cannot be explained by the ferromagnetism in diluted magnetic semiconductors. The magnetic mechanisms in ZnO-based diluted magnetic semiconductors are also discussed. © 2007 Science in China Press.