Controlling the metal insulator transition using the ferroelectric field effect in rare earth nickelates*

A ferroelectric field effect transistor (FE-FET) modulates conductivity in a non-volatile manner by electrostatically accumulating and depleting charge carriers at the interface between a conducting channel and ferroelectric gate. The rare earth nickelate LaNiO$_{3}$ is metallic in bulk, while other rare earth nickelates, such as NdNiO$_{3}$, exhibit metal-insulator transitions and anti-ferromagnetic behavior in the bulk. Here, we show that by coupling the ferroelectric polarization of Pb$_{0.8}$Zr$_{0.2}$TiO$_{3}$ (PZT) to the carriers in a nickelate, we can dynamically induce a metal- insulator transition in ultra-thin films of LaNiO3, and induce large changes in the MIT transition temperature in NdNiO3. Density functional theory is used to determine changes in the physical and electronic Ni-O-Ni bond angle of the nickelate at the interface between PZT and LaNiO3. The effect of the ferroelectric polarization is to decrease the Ni-O-Ni bond angle from 180 degrees and increase the carrier effective mass. Related to this change in electronic structure, we observe a change in resistivity of approximately 80{\%} at room temperature for an ultra-thin 3 unit cell thick film of LaNiO$_{3}$.