Twisting and turning towards new multiferroics

Abstract

Physics 4, 18 (2011) DOI: 10.1103/Physics.4.18 Twisting and turning towards new multiferroics Gavin LawesDepartment of Physics and Astronomy, Wayne State University, Detroit, Michigan 48201, USA Published March 7, 2011 Controlling the rotation and tilt of oxygen octahedra in perovskite structures provides a new route towards room-temperature multiferroics. A Viewpoint on: Hybrid Improper Ferroelectricity: A Mechanism for Controllable Polarization-Magnetization Coupling Nicole A. Benedek and Craig J. Fennie Phys. Rev. Lett. 106, 107204 (2011) – Published March 7, 2011 Magnetoelectric multiferroics are materials that exhibit coupled magnetic and ferroelectric order, and are studied from a desire for electric field control of magnetization [1]. Realizing this promise in new systems provides an interesting challenge for experimentalists and theoreticians alike in the search for candidate materials [2]. The quest is to identify mechanisms that can simultaneously break spatial inversion symmetry to allow ferroelectric order and break time reversal symmetry to allow magnetic order, while also providing a coupling between these two distinct types of order. The search for such materials has provided a number of promising results, including the simultaneous development of strongly coupled magnetic and ferroelectric order in TbMnO3[3], albeit at low temperatures, and the observation of a large ferroelectric polarization in epitaxial BiFeO3[4] films, the as-yet sole example of a room-temperature, single-phase multiferroic. However, despite the concerted research efforts, the discovery of multiferroics exhibiting controllable reversal of the magnetization with an electric field at ambient temperatures has remained elusive.