Charge transfer and hybrid ferroelectricity in (YFeO$_{3}$)$_{n}$/(YTiO$_{3}$)$_{n}$ magnetic superlattices

TL;DR

This paper predicts novel phenomena in (YFeO3)n/(YTiO3)n superlattices, including unconventional charge transfer, hybrid ferroelectricity, and potential metallic ferroelectricity, expanding understanding of oxide heterostructure interfaces.

Contribution

It reveals unexpected charge transfer behavior and hybrid ferroelectricity in these superlattices, highlighting new emergent properties at oxide interfaces.

Findings

Charge transfer opposite to band alignment expectations

Hybrid ferroelectricity with moderate polarization

Persistence of ferroelectric distortion in metallic state

Abstract

Interfaces in oxide heterostructures always provide a fertile ground for emergent properties. Charge transfer from a high energy band to a low energy opponent is naturally expected, as occurring in semiconductor $p$-$n$ junctions. In this study, several exceptional physical phenomena have been predicted in (YFeO$_3$)$_n$/(YTiO$_3$)$_n$ superlattices. First, the charge transfer between these Mott insulators is in opposite to the intuitive band alignment scenario. Second, hybrid ferroelectricity with a moderate polarization is generated in the $n=2$ magnetic superlattice. Furthermore, the ferroelectric-type distortion can persist even if the ($AB$O$_3$)$_2$/($AB$'O$_3$)$_2$ system turns to be metallic, rending possible metallic ferroelectricity.