Room temperature ferromagnetism in HfO2 films

HfO2 films were produced by sputter deposition in the substrate temperature (T-s) range of room temperature (RT)-300 degrees C and their structural, magnetic, and electrical properties were evaluated. The results indicate that the HfO2 films crystallize in the monoclinic structure and are oriented along the (-111) direction. Magnetization measurements (300-1.8 K) evidence their RT ferromagnetism. The effect of T-s is significant on the magnetic moment (M) and coercivity (H-c). M and H-c values enhanced with increasing T-s due to formation of oxygen vacancies. Increase in the temperature from 150 to 300 K decreases H-c without any transition, indicating that the Curie temperature of HfO2 films is higher than RT. Electrical measurements indicate that the HfO2 films are semiconducting. VC 2011 American Institute of Physics. [doi:10.1063/1.3559490]