MIT News June 15, 2020
Kohn anomalies reflect a sudden change in the graph describing a change of the capability of electrons for shielding phonons. This can give rise to instabilities in the propagation of electrons through the material and can lead to many new electronic properties. A team of researchers in the US (MIT, Pennsylvania State University, Argonne National Laboratory, Oak Ridge National Laboratory, NIST, University of Maryland) predicted and observed Kohn anomaly in the topological Weyl semimetal (WSM) tantalum phosphide. It exhibits multiple topological singularities of Weyl nodes, leading to a distinct nesting condition with chiral selection, a power-law divergence, and non-negligible dynamical effects. The work brings the concept of the Kohn anomaly into WSMs and sheds light on elucidating the electron-phonon interaction mechanism in emergent topological materials…read more. TECHNICAL ARTICLE
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)… Credit: Image courtesy of the researchers