2026-05-08 東北大学
図1. (a)超伝導体のCuO2平面における電荷密度波（CDW）を示す模式図。薄い青色と濃い青色の陰影は、それぞれコヒーレンスの高いCDW相と低いCDW相を区別している。赤い矢印は、CDW相のコヒーレンスの変化を示しており、フォノン（緑色の振動）などの集団励起によって位相φの変化として引き起こされる可能性がある。
(b) 理想的なコヒーレント位相で周期性が約4の場合（左上）と、有限の位相変化φを伴うコヒーレント位相の低下の場合（左下）のシミュレーションによるCDWピークプロファイル（右）。
＜関連情報＞
- https://www.tohoku.ac.jp/japanese/2026/05/press20260508-02-CDW.html
- https://journals.aps.org/prl/abstract/10.1103/g41t-8456
超伝導が銅酸化物における電荷密度波の位相コヒーレンスを強化する Superconductivity Reinforces Charge-Density-Wave Phase Coherence across Cuprates
H. Lee, C.-T. Kuo, M. Fujita, C.-C. Kao, and J.-S. Lee
Physical Review Letters Published: 7 May, 2026
DOI: https://doi.org/10.1103/g41t-8456
Abstract
For decades, superconductivity in high-c cuprates has been viewed as a competitor that suppresses charge-density-wave (CDW) order by reducing its amplitude and spatial extent. Here, we show that this picture is incomplete, as superconductivity is accompanied by a systematic enhancement of CDW phase coherence across multiple cuprate families. Using resonant soft x-ray scattering combined with a coherence-sensitive momentum-profile analysis, we uncover a BCS-like growth of phase coherence below c, which phenomenologically manifests as the absence of CDW peak broadening and near-perfect wave-vector locking. This enhancement remains visible even in a disorder-dominated regime created by long-term crystal aging and follows a common trend when compared with published data on Bi-, Hg-, Y-, and Nd-based cuprates. These results indicate that superconductivity reshapes CDW order in two distinct ways, suppressing its amplitude while strengthening its phase coherence, and reveal an additional phase-level interplay with lattice coupling in high-c cuprates.
