Room Temperature Ferroelectric Ferromagnet in 1D Tetrahedral Chain Network

TL;DR

This paper reports the discovery of ferroelectricity and ferromagnetism at room temperature in a one-dimensional FeO4 tetrahedral chain network within a SrFeO2.5 thin film, introducing a new low-dimensional ferroelectric mechanism.

Contribution

It demonstrates ferroelectricity and coupled ferromagnetism in a one-dimensional MOx network, a novel mechanism for low-dimensional ferroelectric materials.

Findings

Room temperature ferroelectricity observed in 1D FeO4 chain

Coupled ferromagnetism detected in the same 1D network

Potential for designing new low-dimensional ferroelectric ferromagnets

Abstract

Ferroelectricity occurs in crystals with broken spatial inversion symmetry. In conventional perovskite oxides, concerted ionic displacements within a three-dimensional network of transition metal-oxygen polyhedra (MOx) manifest spontaneous polarization. Meanwhile, some two-dimensional networks of MOx can foster geometric ferroelectricity with magnetism, owing to the distortion of the polyhedra. Because of the fundamentally different mechanism of ferroelectricity in a two-dimensional network, one can further challenge an uncharted mechanism of ferroelectricity in a one-dimensional channel of MOx and estimate its feasibility. This communication presents ferroelectricity and coupled ferromagnetism in a one-dimensional FeO4 tetrahedral chain network of a brownmillerite SrFeO2.5 epitaxial thin film. The result provides a new paradigm for designing low-dimensional MOx networks, which is expected to benefit the realization of macroscopic ferro-ordering materials including ferroelectric ferromagnets.