Room temperature ferroelectric and magnetic properties of (Co, Li) coimplanted ZnO films

Simultaneous room temperature ferroelectricity and magnetism was observed in (Co, Li) coimplanted ZnO films. The implantation were conducted for Li and Co at energies of 50 and 400 keV, respectively, to doses of 1×1016 and 5×1016 cm−2. Remnant dipole polarization of 10.2 μC/cm2 and coercive electric field of 24.8 kV/cm were recorded for coimplanted ZnO films annealed at 700 °C. The implanted samples annealed at 700 °C also exhibited a saturation magnetization over 11.4×10−5 emu and coercive magnetic field of 67 Oe. The ferroelectricity is interpreted by the ionic radius difference between the dopants and host cations, and the magnetism is explained by bound magnetic polarons mediated by electrons and defects.