Room-temperature Modulation of Microwave Conductivity in Ferroelectric-gated Correlated Oxides

Ferroelectric field-effect transistors (FeFETs) using correlated oxides as the channel materials have attracted strong interest in recent years. For electronic applications, the conductance modulation has to persist up to the operation frequency, which is usually in the gigahertz (GHz) regime. In contrast, conventional studies of FeFETs mostly focus on evaluating the on/off conductance ratio at the DC limit. In this work, we report the nonvolatile modulation of microwave conductivity in ferroelectric PbZr_0.2Ti_0.8O₃-gated ultrathin LaNiO₃/La_0.67Sr_0.33MnO₃ correlated oxide channel visualized by microwave impedance microscopy. The microwave conductivity of the correlated channel underneath the up- and down-polarized domains can be quantified by finite-element analysis. At room temperature, a resistance on/off ratio above 100 between the two polarization states is sustained at frequencies up to 1 GHz, which starts to drop at higher frequencies. The result suggests that the conductance modulation originates from ferroelectric field effect control of carrier density. Our work is significant for potential applications of oxide-based FeFETs in high-frequency nanoelectronics and spintronics.