IISc scientists develop design to control temperature for transition from electrical insulator to conductor

Indian Institute of Science building in Bengaluru
| Photo Credit: SUDHAKARA JAIN

Scientists at Indian Institute of Science (IISc.), in collaboration with scientists from Japan, Denmark and the United States, have developed a synthetic material design that enables them to control the temperature at which a material can overcome electronic ‘traffic jams’ , a transition from an electrical insulator to a conductor, setting the ground for an electronic switch that is more efficient than a transistor.

According to the Department of Science and Technology: “Generally, most commonly encountered materials are either electrical conductors (such as copper or aluminium) or electrical insulators (such as plastic and paper). Correlated electron materials are a class of materials that undergo an electronic transition from an insulator to a metal. However, these transitions work as a function of temperature, making them less useful in devices such as an electronic switch that usually operate at a constant temperature (usually room temperature). Further, these transitions occur at a temperature that might not be relevant for room temperature operations”.

The teams of scientists, including Prof. Naga Phani and his colleagues at the solid state and structural chemistry unit at IISc. Bengaluru, proposed and demonstrated a three-layer structure that comprises of an ‘active’ channel layer that undergoes the metal to insulator transition, a charge reservoir layer that can ‘drip’ electrons into the active layer and control the temperature at which the transition occurs, a charge-regulating spacer layer between the active layer and the reservoir layer which regulates the flow (or ‘drip’) of electrons from the reservoir layer to the active layer.

This research was published in the journal Nature Communications. The novel synthetic materials layer that the researchers proposed eliminates the necessity to add an ‘impurity’ to modify the materials’ properties. Further, the authors developed an easy-to-synthesise and replicate amorphous-layer design for the reservoir and the spacer layers.

This work enables the study and control of properties of these exotic materials that can be both insulators and conductors. Further, this work shows that electronic ‘traffic-jams’ that lead to insulating behaviour in these materials are quite stubborn, and challenge our understanding of correlated electron materials.