Room-temperature multiferroic response in BiFeO3-Bi4Ti3O12 thin film composites obtained by a sustainable method in a fully aqueous medium

Résumé

In the frame of the research in advanced ceramics for microelectronic devices, BiFeO3 films have been one of the most studied candidates due to its high phase-transition temperatures, which could allow it to exhibit ferroelectricity and ferromagnetism at room temperature. However, exploiting the exceptional multiferroic characteristics of BiFeO3-based systems depends largely on controlling thehigh leakage currents that often constrain the ferroelectric response of this material. These leakages can be blocked by reducing the temperature to values close to the liquid nitrogen temperature andthus, the multiferroic response becomes visible. However, at such low temperature, their practicalapplication in commercial devices is obviously constrained. In addition, that unpractical multiferroic behavior is seriously affected by the simultaneous presence of ferroelectricity and ferromagnetism in a sole single-phase material. In this context, efforts need to be redirected to the fabrication of heterogeneous composites system, such as BiFeO3-Bi4Ti3O12, in which both ferroic orders would be present at different phases and the leakages controlled by an adequate doping strategy, leading to a multiferroic behavior at room temperature. Currently, high quality multilayer stacks are being produced using thin film deposition techniques like PLD, MBE, RF magnetron sputtering and the like, which allow a sharp of control over the as-deposited interfaces. All these processes however involve high energy operations in terms of temperature, pressure (high vacuum) and sophisticated equipment; thus being able to precisely assemble those films under softer conditions represents a major challenge. Pursuing this goal, a simple, sustainable processing protocol with high scalability prospects in a fully aqueous medium is here proposed to fabricate exploitable multiferroic thin film systems .