Phonon dynamics in chromium under pressure: Absence of phonon criticality at the approach of the quantum critical point
Year: 2026
Type: article
Abstract: Fermi surface nesting is key to understanding the origin of the itinerant antiferromagnetic spin density wave in chromium. This magnetic order is accompanied by a charge-density wave, and both density waves disappear above the critical pressure $P_c \approx 10$ GPa at low temperatures, defining a quantum critical point. Whether this pressure-induced quantum phase transition is accompanied by a phonon instability remains an open question. Here, we use inelastic x-ray scattering to track the room-temperature acoustic phonon dispersions at pressures up to $P=15.6$ GPa, well above $P_c$. We focus on the Kohn anomalies near the $H$ and $N$ points of the Brillouin zone, with the $H$ point anomaly lying close to the incommensurate spin-density-wave ordering vector. The phonon branches harden smoothly under pressure, while the positions and wave-vector extents of both anomalies remain essentially unchanged across $P_c$, with no additional critical softening. \textit{Ab initio} calculations likewise show that Fermi surface nesting remains robust above $P_c$. These results indicate that the pressure-induced quantum phase transition is not driven by a phonon instability and support a primarily spin-density-wave-driven mechanism in presence of a robust Kohn anomaly.
DOI: 10.1103/f6tk-lf64
Language: English
Subfield: Condensed Matter Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7169203975