The Multiferroic Properties Of Ho And Mn Co-Doping BiFeO₃ Thin Films

Multiferroic materials, which exhibit the coexistence of at least two ferroic properties (ferroelectric, ferromagnetic or, ferroelastic), have been studied extensively due to both their rich physics and their wide potential applications, which opens up an entirely new perspective of magnetic/ferroelectric data storage media, spin-based devices (spintronics), magneto-capacitive devices, magnetic sensors nonvolatile memory, random access memory, etc. As one of representative single phase multiferroics, BiFeO3 (BFO) with perovskite structure, exhibits simultaneously ferroelectric behavior with high ferroelectric Curie temperature and G-type antiferromagnetic behavior with a relatively high Neel temperature. Those advantages make it very attractive from an application point of view. Although BiFeO3 materials have these outstanding advantages, it is difficult to gain a large magnetization and spontaneous polarization, which limits their further applications in magnetoelectric materials. Much work has been carried out to address these difficulties, including adding small amount of substitution or preparing epitaxial films. Among these methods, rare earth iron doped at Bi site and transitional metal doped at Fe site are thought to be effective way to improve the ferroelectric and ferromagnetic properties at room temperature.Based on those above, in this study, pure BiFeO3 (BFO), Bi0.9Hoo.iFeO3 (BHFO), BiFe0.9Mn0.1O3 (BFMO), and Bi0.9Ho0.1Feo.9Mn0.1O3 (BHFMO) thin films were prepared on Pt(100)/Ti/SiO2/Si substrates via a solution-gelation method. The crystal structures, microstructural, ferromagnetic properties, ferroelectric and fatigue properties were investigated. It shows that the ferromagnetic properties, ferroelectric and fatigue properties are obviously improved after doping Ho and Mn. Thus improved performance of the BiFeO3 thin films boils down to the structural transformation and reduced oxygen vacancy concentration. The present work provides an obtainable way on enhancing ferroelectric and fatigue properties of BiFeO3 based thin films.