Resistive switching behavior and improved multiferroic properties of Bi0.9Er0.1Fe0.98Co0.02O3/Co1-xMnxFe2O4 bilayered thin films

摘要

Bilayered Bi0.9Er0.1Fe0.98Co0.02O3/Co1-xMnxFe2O4 (BEFCO/CMxFO) thin films were deposited by the sol gel method. Structural variations between the triclinic-Pi and trigonal-R3c:H (two-phase coexistence) phases in the BEFCO layer were observed owing to the trigonal-R-3m:H phase existing in the CMxFO layer. The oxygen vacancy concentrations of the BEFC0/CMxFO bilayered films are reduced by Mn-doping in the bottom CFO layer. The BEFCO/CFO films showed high oxygen vacancy concentrations with a high leakage current. This induced changes of the significant potential barrier at the interface between the BEFCO and CM(x)FOlayers in the processes of electron capture and release. Thus, the BEFCO/CFO film exhibited obvious resistive switching (RS) effect. The high leakage current also caused a fake polarization phenomenon with a blow up of the P-E loop in the BEFCO/CFO films. However, the real and outstanding ferroelectric properties, which resulted from the fewer oxygen vacancies and the 38% triclinic-P1 structure, were obtained in the BEFCO/CM0.3FO films (Pr similar to 156.3 mu C cm(-2)). In addition, the typical capacitance-voltage curve further confirmed its superior ferroelectric performance. The RS effect almost disappeared in the BEFCO/CM0.3FO bilayered films. Moreover, the enhanced ferromagnetic properties (Ms similar to 100.36 emu cm(-3), M-r similar to 55.38 emu cm(-3)) were obtained for the BEFCO/CM0.1 FO films, which was attributed to the magnetic properties of BEFCO (a more triclinic-Pi phase and numerous Fe2+ ions), in addition to the CMxFO layer. The introduction of the doped magnetic layer into the bilayered films thus represented a highly effective method for enhancing the multiferroic properties of BFO.