A glance at Kohn Anomaly

Diagram depicts the different conditions that give rise to a Kohn anomaly in ordinary metals (at left), versus a material called a Weyl semimetal (at right). The vertical axis shows energy, while the horizontal axis is momentum space. In the conventional metal, a Kohn anomaly can happen when a phonon (q) links two parts of a property called the Fermi surface, which is shown in blue. In the Weyl semimetal, the Kohn anomaly arises when the phonon links two separate Weyl points (kw1-kw2).


Writer: David L. Chandler, MIT News Office
Image: courtesy of the researchers