New measurements reveal distinct fundamental, optical, and transport gaps in ferroelectric oxides, overturning long‑held assumptions about their electronic behaviour Three layers of colour (Courtesy: iStock/Strizh) Ferroelectric materials have a permanent electric dipole, an internal separation of the centres of positive and negative ionic lattices, that can be flipped by applying an electric field. They also undergo a structural change at a material dependent temperature. known as the Curie temperature, above which this dipole behaviour disappears. Despite having permanent dipoles, ferroelectrics are insulating materials. These properties make them valuable in technologies such as sensors, actuators, and memory devices.   In this work, the researchers study the band gaps of ferroelectric materials to better enable their use in energy conversion, catalysis, and optoelectronic devices, where understanding light absorption and electron behaviour is essential.…