Multiferroic metal-PbNb$_{0.12}$Ti$_{0.88}$O$_{3-\delta}$ films on Nb-doped STO

TL;DR

This study reports the discovery of multiferroic metallic behavior in PbNb0.12Ti0.88O3-delta films at room temperature, combining ferroelectricity and metallicity, which challenges traditional understanding and opens new avenues for spintronic applications.

Contribution

It is the first demonstration of multiferroic metallicity in a film, combining experimental evidence with first-principles calculations.

Findings

Multiferroic behavior coexists with metallicity at room temperature.

Oxygen vacancies induce delocalized electrons enhancing ferromagnetism.

Polar displacements and dipoles remain intact despite metallic conduction.

Abstract

Ferroelectricity-the switchable intrinsic electric polarization-has not yet been attained in a metal experimentally and is in fact generally deemed irreconcilable with free carriers, although polar metal has been achieved recently. Multiferroic metal has never even been proposed though multiferroics have been widely investigated. Here we report a room-temperature coexistence of multiferroicity and metallic behavior in PbNb0.12Ti0.88O3-delta films. The oxygen-vacancy-induced electrons become delocalized and ameliorate the ferromagnetic properties of these films, whereas they fail to vanish the polar displacements nor the individual dipole in each unit cell. This concurrent appearance of multiferroicity and metallicity is also confirmed by our first-principles calculation performed on 12.5% Nb-doped PbTiO3 with oxygen vacancies. These findings break a path to multiferroic metallic materials and offer a potential application for multiferroic spintronic devices.