Harnessing the Competing Roles of Charge to Design Ferroelectric-Gated Mott Transistors

We report a record high room temperature resistance switching achieved in ferroelectric PbZr_0.2Ti_0.8O₃ (PZT) gated Mott transistors. We systematically study the ferroelectric field effect in RNiO₃ (R = Sm, Nd, La) and RNiO₃/La_0.67Sr_0.33MnO₃ (LSMO) channels. For single-layer channels, switching PZT polarization induces a metal-insulator transition in the 4 unit cell (uc) LaNiO₃ channel. The resistance switching ratio ΔR/R_on peaks near the electrical dead layer thickness, with the highest ΔR/R_on of 1,619% at 300 K observed in 2 uc LaNiO₃. With the same channel thickness, devices with RNiO₃/LSMO composite channels exhibit up to three orders of magnitude higher ΔR/R_on. A record high ΔR/R_on of 38,540% is observed in the 2.5 uc LaNiO₃/2 uc LSMO bilayer channel, which has been attributed to the interfacial charge transfer effect as it reduces the net carrier density in RNiO₃ without compromising the screening of depolarization field in PZT. First-principles calculations reveal about 0.1 electron/Mn transfer from interfacial Mn to Ni layers, consistent with the atomically resolved EELS results. Studies of the retention and cycling behaviors reveal superior device performance of the PZT/LaNiO₃/LSMO FETs compared with previous reports. Our study addresses one of the critical material challenges that limit the application potential of epitaxial ferroelectric-gated Mott transistors.