The Multiferroic Properties of Zn Doped BiFeO3 Thin Films

BiFe1-xZnxO3 thin films (x = 0, 0.05, 0.1, 0.2, and 0.3) were prepared on LaNiO3 buffered surface oxidized Si substrates using pulsed laser deposition. The effect of Zn dopants on the structural, electrical, magnetic properties, and exchange bias on NiFe layers for BiFeO3 thin films has been systematically investigated. X ray diffraction and Raman spectra show that BiFe1-xZnxO3 thin films have polycrystalline rhombohedral structure with Zn concentration smaller than 5 %, and a large amount of the impurity phase of Bi2Fe4O9 with further increasing Zn concentration above 10 %. With 5 % Zn doping in BiFeO3, the film quality is improved with larger grain size, better ferroelectricity, and larger magnetization. The exchange bias of BiFe1-xZnxO3 on a 3.6 nm thick NiFe layer drastically decreases with increasing Zn doping concentration, and totally disappears with the Zn concentration larger than 10 %, indicating that the canted antiferromagnetic spin structure of BiFeO3 was suppressed with increasing the Zn doping concentration.