Physical properties of multiferroic (1-x) Bi4Ti3O12 – x BiFeO3 composite thin film fabricated by pulsed laser deposition technique for memristor devices: A comparative study

In the digital era, multiferroic materials are attractive due to their simultaneous coupling between ferroelectric and ferromagnetic orders to utilise them for various applications like capacitors, sensors, spintronics, and NVRAM devices. Usually, these material classifications exist in single or composite forms; however, due to the inherent characteristic limitations, hybrid-phase materials are more suitable than single-phase for electronic applications. Keeping this in view, (1-x)Bi₄Ti₃O₁₂ – xBiFeO₃ (x = 0.1 and 0.9) diphasic composite thin film with MIM device configuration has been grown on the ITO-coated glass substrate, prepared by using the Pulsed Laser Deposition technique. The X-ray diffraction pattern confirmed the co-existence of the diphasic composite thin film where a sharp characteristic peak at 2θ ∼ 30.08° has confirmed the phase formation of a bismuth titanate crystal structure associated with a peak at 2θ ∼ 32.10° corresponding to the bismuth ferrite phase. Atomic Force Microscopy investigation indicates that uniform grain growth associated with a lower concentration of oxygen vacancies impacts the smoother surface of the 0.9BIT-0.1BFO than 0.1BIT-0.9BFO thin film samples. The X-ray photoelectron spectroscopy analysis corroborated the Fe-ions and oxygen vacancies in these thin film samples, affecting the material’s ferroelectric and magnetic properties. Interestingly, lesser oxygen vacancies influence the plume dynamic of the 0.9BIT-0.1BFO sample to obtain a smoother and more efficient thin film. It is noteworthy that the P-E characteristic studies of 0.9BIT-0.1BFO thin film exhibited a hysteresis loop with an enhanced magnitude of P_r (∼ 15 μC/cm²) and E_c (∼ 99 kV/cm) due to the lesser oxygen vacancies and domain pinning dynamics than 0.1BIT-0.9BFO sample studied. Hence, this uniformly deposited di-phasic composite thin film configuration could be exploited as a better candidate for capacitors and memory device-based applications.