Interfacial Charge Engineering in Ferroelectric‐Controlled Mott Transistors

Abstract

Heteroepitaxial coupling at complex oxide interfaces presents a powerful tool for engineering the charge degree of freedom in strongly correlated materials, which can be utilized to achieve tailored functionalities that are inaccessible in the bulk form. Here, the charge-transfer effect between two strongly correlated oxides, Sm Nd NiO (SNNO) and La Sr MnO (LSMO), is exploited to realize a giant enhancement of the ferroelectric field effect in a prototype Mott field-effect transistor. By switching the polarization field of a ferroelectric Pb(Zr,Ti)O (PZT) gate, nonvolatile resistance modulation in the Mott transistors with single-layer SNNO and bilayer SNNO/LSMO channels is induced. For the same channel thickness, the bilayer channels exhibit up to two orders of magnitude higher resistance-switching ratio at 300 K, which is attributed to the intricate interplay between the charge screening at the PZT/SNNO interface and the charge transfer at the SNNO/LSMO interface. X-ray absorption spectroscopy and X-ray photoelectron spectroscopy studies of SNNO/LSMO heterostructures reveal about 0.1 electron per 2D unit cell transferred between the interfacial Mn and Ni layers, which is corroborated by first-principles density functional theory calculations. The study points to an effective strategy to design functional complex oxide interfaces for developing high-performance nanoelectronic and spintronic applications.

Modulation of VO2 Metal–Insulator Transition by Ferroelectric HfO2 Gate Insulator

“…[1] One of the ways to mitigate this problem is the use of ferroelectric gating, which can accumulate a vast amount of charge via ferroelectric polarization. [2][3][4] However, ferroelectric gating exhibits the critical drawback of gate leakage. The majority of the ferroelectric materials have large dielectric constants; consequently, a large current leakage is observed because the dielectric constant is anti-correlated with the band gap.…”

Tailoring Materials for Mottronics: Excess Oxygen Doping of a Prototypical Mott Insulator

“…Detuning the band‐filling, e.g., by applying an external electric field, can trigger the Mott transition (MT) into the correlated metal phase rendering all previously localized electrons mobile in the ON‐state . Besides the large ON/OFF ratio and fast switching speed in such devices, the high charge carrier concentration allows for further miniaturization beyond the current limits set by the extremely small number of carriers in nanoscale semiconductor devices …”

“…Such high fields can indeed be achieved by liquid ion gating, which was successfully applied to demonstrate the advanced functionalities of Mott transistors in VO 2 and NdNiO 3 but may not be suitable for scalable electronics . An alternative approach uses the strong polarization of a ferroelectric layer to significantly alter the charge carrier concentration of an adjacent Mott insulating channel material …”

Assembly of Close‐Packed Ferroelectric Polymer Nanowires via Interface‐Epitaxy with ReS2

“…The corresponding coercive field ( E c ) is about 0.05 V nm −1 or less, which is significantly lower than the films prepared by the LB [ 25,26 ] method (0.1–1 V nm −1 ) and becomes comparable with those of the oxide ferroelectrics. [ 27 ] Such low E c can be attributed to the out‐of‐plane polar orientation of the P‐NW films. Unlike the polycrystalline LB films, where the polarization points 30° away from the film normal, [ 28 ] the P‐NWs crystalize along the polar axis (Figure 2f), requiring a significantly reduced switching field due to the polar anisotropy.…”