Phonon dynamics in Chromium under pressure: absence of phonon criticality at the approach of the quantum critical point
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 Pc ≈ 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 Pc. 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 Pc, with no additional critical softening. \textit{Ab initio} calculations likewise show that Fermi surface nesting remains robust above Pc. 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.
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BibTeX
@misc{rodiere2026phonon,
title = {{Phonon dynamics in Chromium under pressure: absence of phonon criticality at the approach of the quantum critical point}},
author = {P. Rodière and J. E. Lorenzo and Q. N. Meier and L. Paolasini and A. Bosak},
howpublished = {arXiv},
year = {2026},
month = aug,
doi = {10.48550/arxiv.2607.18015},
eprint = {2607.18015},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2607.18015},
note = {CC BY-NC-SA 4.0},
}
RIS
TY - UNPB
TI - Phonon dynamics in Chromium under pressure: absence of phonon criticality at the approach of the quantum critical point
AU - P. Rodière
AU - J. E. Lorenzo
AU - Q. N. Meier
AU - L. Paolasini
AU - A. Bosak
PY - 2026
DA - 2026/08/06
PB - arXiv
DO - 10.48550/arxiv.2607.18015
UR - https://arxiv.org/abs/2607.18015
AB - 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 ≈ 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.
ER -