Ferroelectricity is a characteristic of certain materials that have a spontaneous electric polarization that can be reversed by the application of an external electric field. All ferroelectrics are pyroelectric, with the additional property that their natural electrical polarization is reversible. 

Multiferroics are attracting increasing interest not only due to the profound underlying physics (i.e., the coexistence and coupling of ferroelectric and magnetic orders), but also the potential applications in novel multifunctional devices. In particular, multiferroics may be used to realize non-volatile, low-power, and high-density memory devices that combine fast electrical writing and magnetic reading.