Room-temperature ferromagnetism in epitaxial p-type K-doped ZnO films
- Department of Applied Physics, Institute of Advanced Materials Physics, Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology, Faculty of Science, Tianjin University, Tianjin 300072, PR China
- Received 6 August 2013
- Revised 10 December 2013
- Accepted 22 December 2013
- Available online 28 December 2013
- Communicated by H. Akai
Epitaxial K-doped ZnO films were deposited on c-Al2O3 substrates by RF-magnetron sputtering system.
A conversion of conductivity from n-type to p-type was observed with increasing the K concentration.
The effect of K-doping and annealing on the ferromagnetism of ZnO films were examined.
The origin of the ferromagnetism was discussed using first-principle calculations.
Room-temperature ferromagnetism with p-type conductivity was observed in epitaxial K-doped ZnO films prepared by RF-magnetron sputtering. The coincident changes in the electrical, optical and magnetic properties indicate that the cation holes play important roles in mediating the ferromagnetism in K-doped ZnO films. The maximum saturation magnetization of 8 emu/cm3 was obtained in the 8% K-doped film and the thermal annealing in air could stabilize the ferromagnetic signature. Finally, first-principle calculations reveal that the magnetic properties in K-doped ZnO films are attributed to the strong p-p interaction between the unpaired 2p electrons at O sites.