Engineering of multiferroic BiFeO3 grain boundaries with head-to-head polarization configurations

Confined low dimensional charges with high density such as two-dimensional electron gas (2DEG) at interfaces and charged domain walls in ferroelectrics show great potential to serve as functional elements in future nanoelectronics. However, stabilization and control of low dimensional charges is challenging, as they are usually subject to enormous depolarization fields. Here, we demonstrate a method to fabricate tunable charged interfaces with similar to 77 degrees, 86 degrees and 94 degrees head-to-head polarization configurations in multiferroic BiFeO3 thin films by grain boundary engineering. The adjacent grains are cohesively bonded and the boundary is about 1 nm in width and devoid of any amorphous region. Remarkably, the polarization remains almost unchanged near the grain boundaries, indicating the polarization charges are well compensated, i.e., there should be two-dimensional charge gas confined at grain boundaries. Adjusting the tilt angle of the grain boundaries enables tuning the angle of polarization configurations from 71 degrees to 109 degrees, which in turn allows the control of charge density at the grain boundaries. This general and feasible method opens new doors for the application of charged interfaces in next generation nanoelectronics. (C) 2020 Science China Press. Published by Elsevier B.V. and Science China Press. All rights reserved.

Automated summary

By using grain boundary engineering, tunable charged interfaces with head-to-head polarization configurations can be fabricated in multiferroic BiFeO3 thin films. Adjusting the tilt angle of the grain boundaries allows for tuning the angle of polarization configurations and control of charge density at the grain boundaries, providing new opportunities for the application of charged interfaces in next generation nanoelectronics.