Designing new ferroelectrics with a general strategy

Abstract

The presence of a switchable spontaneous electric polarization makes ferroelectrics ideal candidates for the use in many applications such as memory and sensors devices. Since known ferroelectrics are rather limited, finding new ferroelectric materials has become a flourishing field. One promising route is to design the improper ferroelectrics. However, previous approach based on the Landau theory is not easily adopted for systems that are unrelated to the Pbnm perovskite structure. To this end, we develop a general design rule that is applicable to any system. By combining this rule with the density functional theory calculations, we identify previously unrecognized classes of ferroelectric materials. It is shown that the $R\bar{3}c$ perovskite structure can become ferroelectric by substituting half of the B-site cations. Compound ZnSrO₂ with a non-perovskite layered structure can also be ferroelectric through the anion substitution. Moreover, our approach can be used to design new multiferroics as illustrated in the case of fluorine substituted LaMnO₃.

Ferroelectricity: General approach for designing new ferroelectric materials

An innovative computational method could enable the design of new classes of ferroelectric materials. Ferroelectrics, whose spontaneous electric polarizations can be switched electrically, are useful for a range of applications, such as memory or sensing devices. However, relatively few naturally occurring materials are ferroelectric, and, while theoretical methods for designing new ferroelectrics are available, they are usually restricted to highly symmetric systems such as perovskite oxides. A team led by Hongjun Xiang from Fudan University have now developed a more general computational approach that can be applied to any system, and have used it to identify previously unrecognized classes of ferroelectrics. Such an approach could not only enable new ferroelectrics to be discovered, but it may also be suitable for designing multiferroic systems.