Electric field–induced tunable insulator-to-metal transition at room temperature in NiO/ferroelectric heterostructures

This paper presents a wafer-scale NiO (a prototype Mott material)/ferroelectric heterostructure termed as ferroelectric Mott (FeMott), which is capable of room-temperature operations as a gate tunable electrical switch, in deep contrast with several existing Mott transistors that operate at around 70°C and are based on VO₂, which is the most widely used Mott material. Here, FeMott devices made using NiO illustrate a reversible insulator-metal transition (IMT), which was first investigated by Mott and referred as the first known Mott material. We show that integrating NiO with an yttrium-doped HfO₂(HfYO) ferroelectric layer enables electrical switching through an electrically induced IMT. This switching mechanism is attributed to the electronic interactions between NiO and HfYO, which possess a significant remanent polarization of 80<i>μ</i>C cm^-2and a coercive electric field of 2.7 MV cm^-1at room temperature. The device exhibits a gate voltage control of the IMT starting at 1<i>μ</i>V, resulting in a high ON/OFF ratio of five orders of magnitude.