Quasi-One-Dimensional Fermi Surface Nesting and Hidden Nesting Enable Multiple Kohn Anomalies in α -Uranium

Abstract

The topology of the Fermi surface controls the electronic response of a metal, including charge density wave (CDW) formation. A topology conducive for Fermi surface nesting (FSN) allows the electronic susceptibility ${\chi }_0$ to diverge and induce a CDW at wave vector ${\mathbf{q}}_{\mathrm{CDW}}$. Kohn extended the implications of FSN to show that the imaginary part of the lattice dynamical susceptibility ${\chi }_L^{\prime \prime }$ also responds anomalously for all phonon branches at ${\mathbf{q}}_{\mathrm{CDW}}$—a phenomenon referred to as the Kohn anomaly. However, materials exhibiting multiple Kohn anomalies remain rare. Using first-principles simulations of ${\chi }_0$ and ${\chi }_L^{\prime \prime }$, and previous scattering measurements [Crummett et al., Phys. Rev. B 19, 6028 234 (1979)], we show that $\alpha$-uranium harbors multiple Kohn anomalies enabled by the combined effect of FSN and “hidden” nesting, i.e., nesting of electronic states above and below the Fermi surface. FSN and hidden nesting lead to a ridgelike feature in the real part of ${\chi }_0$, allowing interatomic forces to modulate strongly and multiple Kohn anomalies to emerge. These results emphasize the importance of hidden nesting in controlling ${\chi }_0$ and ${\chi }_L^{\prime \prime }$ to exploit electronic and lattice states and enable engineering of advanced materials, including topological Weyl semimetals and superconductors.