AI 中文总结
研究铬在压力下声子动力学，通过非弹性X射线散射实验及第一性原理计算发现，虽临界压力以上声子异常软化仍存在，但在反铁磁有序中作用不大，费米面嵌套在压力下的稳健性解释了科恩异常存在的原因。
AI 中文摘要
费米面嵌套是理解铬中巡游反铁磁自旋密度波起源的关键。在极低温下，该密度波在临界压力\(P_c\approx10\)GPa以上被破坏，定义了一个量子临界点。强电子 - 声子耦合在布里渊区的\(H\)点附近诱导了小的声子软化。本文进行了高达\(P = 15.6\)GPa（远高于临界压力\(P_c\)）的压力下声子色散曲线的非弹性X射线散射实验。结果表明著名的声子异常软化仍然存在，这意味着它们在反铁磁有序中不起主要作用。基于第一性原理计算，费米面嵌套在压力下的稳健性解释了临界压力以上这些科恩异常的存在。
英文摘要
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.
Commentsaccepted in Phys. Rev. B
Journal refPhys. Rev. B 114, 084304 (2026)
