Room temperature ferromagnetism of Fe-implanted ZnO film

The ZnO-based diluted magnetic semiconductors (DMSs) with room temperature ferromagnetism were achieved by ion implantation. Fe+ ions at 80 keV with doses ranging from 1x10(16) to 8x10(16) cm(-2) were implanted into n-type ZnO films at room temperature. Subsequently, the samples were annealed at 700 degrees C for 1 h in air ambient. The Fe-implanted content was determined by proton induced x-ray emission. The magnetic property was measured by the Quantum Design MPMS superconducting quantum interference device magnetometer. No trace of secondary phases or clusters was observed within the sensitivity of x-ray diffraction. Raman spectrum showed that the Fe ions replaced Zn atoms and incorporated into the crystal lattice positions of ZnO. Apparent ferromagnetic hysteresis loops measured at 300 K were observed, and the temperature-dependent magnetization showed that their Curie temperature exceeded room temperature.