Charge Engineering in Nickelate-based Mott Transistors Gated by Ferroelectrics*

We present a comprehensive study of ferroelectric-gated Mott transistors based on high quality epitaxial heterostructures composed of a ferroelectric Pb(Zr,Ti)O₃ (PZT) gate and a correlated oxide RNiO₃ (R = La, Nd, Sm) channel. For single layer nickelate channels, including Sm_0.5Nd_0.5NiO₃, NdNiO₃ (NNO), and LaNiO₃ (LNO), the resistance switching ratio ΔR/R_on increases exponentially with decreasing channel thickness until it approaches the electrical dead layer thickness, with the maximum ΔR/R_on~194% observed in 1 nm LNO channel. Inserting a La_1-xSr_xMnO₃ (LSMO) buffer layer results in up to two orders of magnitude increase in ΔR/R_on for devices with the same total channel thickness, with the maximum ΔR/R_on reaching 1,225% in the NNO/LSMO channel. The giant enhancement is attributed to the interfacial charge transfer effect between RNiO₃ and LSMO, which effectively reduces the carrier density in the active channel. Our studies address the key materials challenges that limit the application potential of epitaxial complex oxide-based field effect transistors.