Ferroelectric nematic liquid crystal, a century in waiting

In this issue of PNAS, the liquid crystal group of the Soft Materials Research Center at the University of Colorado Boulder, led by N.A. Clark, reports on the discovery of a ferroelectric nematic fluid NF, a new state of matter. Such a phase has been expected at least since 1916 but first-principle experiments have never demonstrated its existence until now. We describe the main features of ferroelectric nematics and how their topological defects are different from those in other ordered media.