[39] Structural and magnetic properties of Ge_0.7Mn_0.3 thin films

Ge_0.7Mn_0.3 thin films were fabricated on Al₂O₃ (0001) and glass substrates at growth temperatures ranging from room temperature to 500 °C by a radio frequency magnetron sputtering. We found that the Ge_0.7Mn_0.3 thin films showed a polycrystalline-to-amorphous transition at about 360 °C, and the ferromagnetic transition temperature of each thin film depends on its structure — crystalline or amorphous states. Particularly, the Ge_0.7Mn_0.3 thin films showed room temperature ferromagnetism when they were fabricated at temperatures above the crystallization temperature.