Metal alloy with heat control

Researchers have discovered an electronic property at the frontier between the thermal and quantum sciences in a specially engineered metal alloy — and in the process identified a promising material for future devices that could turn heat on and off with the application of a magnetic “switch.”

In this material, electrons move like massless photons or light, which is an unexpected behavior but a phenomenon theoretically predicted to exist here. The alloy was engineered with the elements bismuth and antimony at precise ranges based on foundational theory.

Researchers found that under the influence of an external magnetic field, these oddly behaving electrons manipulate heat in ways not seen under normal conditions. On both the hot and cold sides of the material, some electrons generate heat, or energy, while others absorb energy, effectively turning the material into an energy pump. The result is a 300% increase in thermal conductivity.

The cones illustrate the equations of motion of electrons when an external magnetic field is applied to the bismuth alloy engineered for the study. Green lines and purple lines represent electrons that generate and absorb energy, respectively. image courtesy of Renee Ripley

If the magnet is taken away, the mechanism turns off.

“The generation and absorption form the anomaly,” said study senior author Joseph Heremans, professor of mechanical and aerospace engineering and Ohio eminent scholar in nanotechnology at Ohio State University. “The heat disappears and reappears elsewhere. It is like teleportation. It only happens under very specific circumstances predicted by quantum theory.”