Interfacial Multiferroics of TiO2/PbTiO3 Heterostructure Driven by Ferroelectric Polarization Discontinuity

TL;DR

This paper demonstrates that ferroelectric polarization discontinuity at TiO2/PbTiO3 interfaces can induce conductive and magnetic states, revealing a new pathway for interfacial multiferroics with potential applications in electronics and spintronics.

Contribution

It introduces a novel interfacial mechanism driven by ferroelectric polarization discontinuity, distinct from polar discontinuity, to generate multiferroic states in oxide heterostructures.

Findings

Interfacial charge transfer creates conductive states with ferromagnetism.

Strong coupling between ferroelectric polarization and interface magnetism.

Potential for room-temperature multiferroic applications.

Abstract

Novel phenomena appear when two different oxide materials are combined together to form an interface. For example, at the interface of LaAlO3/SrTiO3, two dimensional conductive states form to avoid the polar discontinuity and magnetic properties are found at such interface. In this work, we propose a new type of interface between two nonmagnetic and nonpolar oxides that could host a conductive state with magnetic properties, where it is the ferroelectric polarization discontinuity instead of the polar discontinuity that leads to the charge transfer, forming the interfacial conductive or magnetic states. As a concrete example, we investigate by first-principles calculations the heterostructures made of ferroelectric perovskite oxide PbTiO3 and non-ferroelectric polarized oxides TiO2. We show that charge is transferred to the interfacial layer forming an interfacial conductive state with ferromagnetic ordering that may persist up to room temperature. Especially, the strong coupling between bulk ferroelectric polarization and interface ferromagnetism represents a new type of magnetoelectric effect, which provides an ideal platform for exploring the intriguing interfacial multiferroics. The findings here are important not only for fundamental science but also for promising applications in nanoscale electronics and spintronics.