Newly observed phenomena could open the door to new quantum devices

Researchers at MIT have discovered an unexpected type of material exhibiting an exotic physical phenomena known as a Kohn anomaly. Researchers at MIT and elsewhere believe that the finding could provide new insights into certain fundamental processes that help determine why metals and other materials displayed complex electronic properties underlining technology today. The team says the way electrons interact with phonons, which are vibrations passing through her crystalline material, determines the physical process that takes place inside many electronic devices.

These interactions have been difficult to study in detail because they are generally very weak. However, the new study found a new and more durable kind of unusual electron-phonon interaction known as a Kohn anomaly. The anomaly was previously believed to exist only in conductive materials like graphene, but was discovered in an exotic material called a topological Weyl semimetal. In this case the Weyl semimetal was tantalum phosphide. The finding could help shed light on important aspects of the complex interplay between electrons and phonons, according to the scientists.

The new finding, which is based on both theoretical predictions and experimental observations, was described this weekend on paper by MIT graduate students Thanh Nguyen and Nina Andrejevic, postdoc Ricardo Pablo-Pedro, Research Scientist Fei Han, Professor Mingda Li, and 14 others at MIT and several other universities and national laboratories. To measure the interactions, the team used advanced neutron and X-ray scattering probes at three national laboratories to probe the behavior of the tantalum phosphide material.

Researchers say they predicted there was a Kohn anomaly in the material based on theory. They were able to guide experiments to the point where they wanted to search for the phenomenon and were able to see a good agreement between theory and the experiments.

Researchers say that a better understanding of the electron-phonon couplings could lead the way to develop materials such as better high-temperature semiconductors or fault-tolerant quantum computers. The team says since the materials are so new, they need time to think about what the materials could do.