Depth profiling charge accumulation from a ferroelectric into a doped Mott insulator

TL;DR

This study combines advanced microscopy, spectroscopy, and theory to quantitatively analyze charge distribution at the ferroelectric/oxide interface, revealing insights for improving oxide-based electronic switching.

Contribution

It provides the first atomic-scale, quantitative characterization of polarization-induced charge density changes at a ferroelectric/doped Mott insulator interface.

Findings

Charge accumulates at the interface in a measurable way.

Interface engineering can enhance switching effects.

Atomic-scale insights inform device design.

Abstract

The electric field control of functional properties is a crucial goal in oxide-based electronics. Non-volatile switching between different resistivity or magnetic states in an oxide channel can be achieved through charge accumulation or depletion from an adjacent ferroelectric. However, the way in which charge distributes near the interface between the ferroelectric and the oxide remains poorly known, which limits our understanding of such switching effects. Here we use a first-of-a-kind combination of scanning transmission electron microscopy with electron energy loss spectroscopy, near-total-reflection hard X-ray photoemission spectroscopy, and ab-initio theory to address this issue. We achieve a direct, quantitative, atomic-scale characterization of the polarization-induced charge density changes at the interface between the ferroelectric BiFeO3 and the doped Mott insulator Ca1-xCexMnO3, thus providing insight on how interface-engineering can enhance these switching effects.